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REVIEW 3 major objections 5 minor 25 references

Precession-free domain wall dynamics in compensated ferrimagnets

T0 review · 3 major / 5 minor · reviewed 2026-08-14 · deepseek-v4-flash

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Pith's one-line read Spin-orbit-torque-driven domain walls in a GdFeCo/Pt ferrimagnetic track stop precessing exactly at the angular momentum compensation temperature, where the effective damping diverges.

desk verdict A genuinely new differential method for finding TMC and TAC in ferrimagnetic DWs, with a credible but model-dependent case for precession-free motion at TAC. read the letter →

arxiv 1908.08867 v2 pith:MDAJSW3F submitted 2019-08-23 cond-mat.mtrl-sci cond-mat.mes-hall

E. Haltz , J. Sampaio , S. Krishnia , L. Berges , R. Weil , A. Mougin This is my paper · ORCID
classification cond-mat.mtrl-scicond-mat.mes-hall
keywords ferrimagnetsdomainwalldynamicsspin-orbittorqueangularmomentumcompensationtemperatureprecession-freeGdFeCo/Pttransversein-planefieldeffectivedampingdivergence
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper aims to establish that in a ferrimagnetic GdFeCo film on platinum, magnetic domain walls driven by spin-orbit torque stop precessing exactly at the angular momentum compensation temperature $T_\mathrm{AC}$, where the net angular momentum of the two antiparallel sublattices cancels. At that temperature the wall remains in the Néel configuration and moves with a mobility around 1.2 (m/s)/(GA/m²), about ten times larger than earlier reports. The authors locate $T_\mathrm{AC}$ without any material parameters by applying a transverse in-plane field $H_Y$ and tracking the two temperatures at which the velocity difference between $+H_Y$ and $-H_Y$ crosses zero; these are the magnetization and angular momentum compensation points. If correct, the result confirms the predicted divergence and sign change of the effective damping and explains a practical route to faster, lower-power spintronics in multi-sublattice materials.

What carries the argument

The load-bearing object is the angle balance for the domain wall magnetization (Eq. 2), $\varphi = \arctan\bigl(\cdots\bigr)$, in which the SOT contribution is divided by the effective damping $\alpha_\mathrm{eff}$. In a ferrimagnet both the net magnetization $M_S$ and $\alpha_\mathrm{eff}$ change sign at their respective compensation temperatures; the divergence of $\alpha_\mathrm{eff}$ at $T_\mathrm{AC}$ suppresses the current-induced rotation of $\varphi$, while the transverse field $H_Y$ rotates $\varphi$ oppositely in the two sublattice-dominance regimes. Detecting where $\Delta v$ changes sign therefore converts a symmetry of the internal wall angle into a parameter-free thermometer for $T_\mathrm{MC}$ and $T_\mathrm{AC}$.

What would settle it

Re-measure $\Delta v(T_{SP})$ while reading the track temperature directly from, say, the film's own resistivity or a calibrated microthermometer; if the second crossing $T_2$ no longer occurs at a single temperature when $J$ is varied, or if that temperature disagrees with $T_\mathrm{AC}$ from ferromagnetic resonance or pump-probe measurements, the central identification of $T_2$ as $T_\mathrm{AC}$ fails.

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Extended reading notes

Core claim

In a GdFeCo/Pt track, domain walls driven by spin-orbit torque move according to $v\propto\cos\varphi$, where $\varphi$ is the angle of the wall magnetization, set by the competition of DMI, SOT, and the applied transverse field $H_Y$. The paper's central claim is that at the angular momentum compensation temperature $T_\mathrm{AC}$, the effective damping $\alpha_\mathrm{eff}$ diverges and changes sign, so the SOT-induced torque has no effect on $\varphi$: the wall remains in the Néel configuration ($\varphi=0$) and its motion is precession-free, reaching a mobility near 1.2 (m/s)/(GA/m²). By measuring the velocity difference $\Delta v = v(+H_Y)-v(-H_Y)$ as a function of temperature and current, the authors find two crossing temperatures $T_1=312$ K and $T_2=334$ K where $\Delta v=0$; they identify $T_1$ as the magnetization compensation temperature $T_\mathrm{MC}$ and $T_2$ as $T_\mathrm{AC}$. Because the crossings come from the symmetry of the response to $H_Y$, the determination does not require material parameters and, unlike the mobility-peak method, is not shifted by pinning.

Load-bearing premise

Every temperature assigned to the track, including the claims that the $\Delta v=0$ crossings mark $T_\mathrm{MC}$ and $T_\mathrm{AC}$, rests on the Joule-heating law $T = T_{SP} + a J^2$ with a single fitted coefficient $a$ that is assumed not to depend on current polarity, applied field, or temperature; the paper itself uses two different values of $a$ for different fits.

Editorial extensions

If this is right

  • At $T_\mathrm{AC}$, SOT-driven walls in compensated ferrimagnets should move with no precessional energy loss, which accounts for the observed record mobility and points to faster, lower-power switching at the compensation point.
  • The $\Delta v=0$ crossing at $T_2$ gives $T_\mathrm{AC}$ directly from experiments without knowing the DMI strength, spin Hall angle, or damping, so the method can be applied to any material with two antiparallel sublattices.
  • Below $T_\mathrm{MC}$ and above $T_\mathrm{AC}$, the sign of $\Delta v$ reveals which sublattice dominates and which way the wall precesses, giving a sublattice-resolved probe of the dynamics.
  • The data support the picture that multi-sublattice materials near angular momentum compensation combine antiferromagnet-like fast dynamics with ferromagnet-like spin transport and detectability.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The same transverse-field asymmetry should work for field-driven domain walls: since the SOT term drops out of the angle balance, the $H_Y$ response still flips at $T_\mathrm{MC}$, and at $T_\mathrm{AC}$ the field-driven mobility peak should be free of the pinning shifts seen for the current-driven mobility peak.
  • Because the method relies only on the existence of two antiparallel spin lattices, it could be transferred to synthetic ferrimagnets or antiferromagnetically coupled multilayers, where $T_\mathrm{AC}$ can be tuned by layer thickness.
  • The paper uses one quadratic Joule-heating coefficient for the crossing-point fits and another for the mobility-peak fit; an independent measurement of the track temperature would decide which coefficient is physical and would shift the inferred $T_\mathrm{AC}$ if the mismatch is real.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. The manuscript reports measurements of spin-orbit-torque-driven domain wall motion in a ferrimagnetic GdFeCo/Pt track as a function of sample-holder temperature, current density, and a transverse in-plane field. The authors observe a peak in DW mobility that they attribute to a single track temperature, a non-monotonic velocity-versus-current response, and two temperatures at which the velocity difference between opposite transverse fields changes sign. They interpret these two crossing points as the magnetic compensation temperature (TMC) and the angular momentum compensation temperature (TAC), and conclude that at TAC the DW remains in a Néel configuration with vanishing precession and that the effective damping diverges. The paper proposes a new method for determining TAC that, the authors claim, is robust and parameter-free.

Significance. If the central claim is correct, the work provides a direct experimental confirmation of the long-standing prediction that the DW precession term vanishes at the angular momentum compensation point in compensated ferrimagnets, and it offers a practical electrical/optical method for locating TAC in device-relevant tracks. The reported record mobility and the large, sign-changing asymmetry under transverse fields are striking and potentially of broad interest for spintronics. The paper also benefits from a clear experimental design: the crossing-point analysis uses an experimental observable (Δv=0) rather than a pure model fit, and the supplementary material provides the full velocity data, mean-field calculations, and parameter values used in the 1D model. That said, the support for the TAC assignment is currently weakened by calibration inconsistencies and by model dependence in the reconstruction of the internal DW angle, as detailed below.

major comments (3)
  1. [§3, Fig. 2c vs Fig. 3c] The Joule heating calibration is inconsistent between the two central figures. In Fig. 2c the mobility maxima are fitted with TSP = 342 K - 0.00013 J^2, while in Fig. 3c the crossing points are fitted with TSP,i = Ti - 0.00008 J^2. Because the entire determination of TAC depends on converting TSP to the actual track temperature T, this ~40% discrepancy in the quadratic coefficient a is load-bearing. For J = 600 GA/m^2 the difference in the inferred temperature is about 18 K, which is larger than the claimed 8 K difference between TAC (342 K from Fig. 2) and the new crossing-point value (334 K). The authors should either reconcile these two calibrations with a single heating law, quantify the uncertainty in a, or explicitly discuss why the two analyses yield different coefficients.
  2. [§3, 'Parameter-free' claim, and TAC identification] The abstract and §3 state that the new method provides a 'robust and parameter-free measurement of TAC'. This is overstated in two ways. First, converting the measured TSP to track temperature T uses the fitted quadratic coefficient a, which is a fit parameter; the crossing temperatures T1 and T2 are therefore not parameter-free. Second, the identification of the second crossing point T2 as TAC relies on the model interpretation in Fig. 3d, namely that the sign change of Δv across T2 arises from the sign change of the effective damping α_eff, which is itself the quantity the paper claims to demonstrate. The experimental observable Δv=0 is robust, but its assignment to TAC is model-dependent and should be justified more carefully, for example by comparing with an independent measurement of TAC or by showing that alternative interpretations (e.g., a sign change of the DMI or of the spin Hall angle) are excluded by the data.
  3. [§3 and Supplemental Material, Eq. 2 analysis] The reconstruction of the DW internal angle φ(T) and the conclusion that α_eff diverges at TAC rely on the 1D model with an α(T) function that is 'chosen to best reproduce the shape of the experimental curves' (Supplemental Material). This means the excellent agreement in Fig. 3f is partly a fit, not an independent prediction. The authors should state explicitly which aspects of the data are used to constrain α(T) and which aspects are tests of the model, and they should provide a robustness check showing that the identification of T2 as TAC is insensitive to reasonable variations of the assumed α(T) shape. Without such a check, the claim that the propagation is precession-free at TAC is inferred rather than directly established.
minor comments (5)
  1. [Abstract] There is a typographical error: 'magnetic textures, We demonstrate' should be 'magnetic textures. We demonstrate'.
  2. [Fig. 3c caption] The caption reads 'T2 = 312 K, T2 = 334 K'; this should be 'T1 = 312 K, T2 = 334 K'.
  3. [§3, Fig. 3c] The text says the fits of TSP,1(J) and TSP,2(J) give the same heating parameter a within 1%, but no error bars or fit residuals are shown. The claimed precision of the crossing points and of the inferred temperatures would be more convincing with an explicit uncertainty analysis.
  4. [References] Reference [22] is given as a placeholder with an empty URL; the full supplementary citation should be provided.
  5. [General] The stress-test note appended to the manuscript concerns Hölder continuity and C^1 estimates on compact manifolds in a PDE context; this is unrelated to the present experimental condensed-matter paper, and no such regularity claims appear in the manuscript.

Circularity Check

2 steps flagged · score 6.0 of 10

The Δv=0 crossing is an honest observable, but the model 'agreement' and the inferred α_eff divergence are circular because α(T) was fitted to the curves.

  1. fitted input called prediction [Supplemental Materials, 'Analytical model of DW velocity under SOT and field'; main text, Eq. 2 and closing paragraph of Section 3.]
    "The only parameter that is not experimentally determined, α(T), is approximated by an inverse linear law ..., chosen to best reproduce the shape of the experimental curves (see Fig. 3a and f). (...) At T = TAC, the SOT-driven DW remains Neel (φ=0) and the propagation is precession-free which shows that the effective damping 𝛼J__ diverges (Eq. 2)."

    α(T) is not measured; an inverse-linear divergent form is assumed and explicitly tuned to reproduce the velocity curves. The same model is then used to reconstruct φ(T) and to claim that the data show α_eff diverging at TAC. The divergence is therefore an input of the calculation, not an output of the experiment. The experimental Δv=0 crossing is real, but the statement that it is TAC and that α_eff diverges is read out of the fitted α(T), so this part of the argument reduces to its own fitting assumption.

  2. fitted input called prediction [Main text, Section 3 (Fig. 3g), paragraph beginning 'All the normalised Δv/‹v›...']
    "All the normalised Δv/‹v› can be superimposed on the same graph versus T in Fig. 3g using the obtained Joule heating law. The envelope corresponds to the calculated Δv/‹v› for J between 150 and 450 GA/m² using eq. 1 and 2, with an excellent agreement."

    The 'excellent agreement' between the envelope and the data is not an independent prediction. The Joule heating law was fitted to the same crossing points that define the temperature axis, and α(T) was chosen to best reproduce the experimental curves. Thus the overlay in Fig. 3g is a consistency check of fitted quantities rather than a parameter-free confirmation of the model.

full rationale

The paper's core experimental observation is not circular: the two crossings TSP,1 and TSP,2 in Δv(TSP) are directly measured, and the identification of T1 with TMC and T2 with TAC uses established ferrimagnet compensation physics (divergence of α_eff and sign changes), cited to independent prior work. No load-bearing self-citation chain or uniqueness theorem is involved; refs. [2,3] are the authors' own but only supply sample properties and spin-transport characterization, not the central inference. However, the paper overstates the model comparison as validation. The supplemental states that α(T) is an inverse-linear function 'chosen to best reproduce the shape of the experimental curves,' and the main text then uses the resulting 'excellent agreement' to reconstruct φ(T) and to conclude that α_eff diverges at TAC. That conclusion is baked into the assumed α(T), making the model-based part of the claim circular. The fitted Joule-heating calibration also differs between Fig. 2c (a = 0.00013) and Fig. 3c (a = 0.00008), which is a correctness/calibration risk rather than a circularity, but it further undermines the 'parameter-free' wording. Overall, the central experimental finding has independent content, so this is partial circularity, not a fully self-referential derivation.

Assumptions & free parameters 3 free parameters · 4 assumptions · 0 invented entities

The paper introduces no new physical entities. Its free parameters are the Joule heating coefficient and the effective damping parametrization, both fitted to data. The central interpretation rests on established 1D DW model assumptions and effective-parameter mappings for ferrimagnets.

free parameters (3)
  • Joule heating coefficient a = 0.00008 K/(GA/m^2)^2 (Fig. 3c); 0.00013 K/(GA/m^2)^2 (Fig. 2c)
    Used to convert sample holder temperature TSP to track temperature T via T = TSP + a J^2. The two reported values differ, and the inferred TMC and TAC depend on this conversion.
  • Effective damping alpha_eff(T) = Approximated by an inverse linear law, constant chosen by hand to fit experimental curve shapes
    Used in the 1D model to reproduce the experimental velocity and Δv curves. The 'excellent agreement' in Fig. 3f depends on this chosen parameter.
  • Ms temperature shift = 25 K shift applied to Ms(T) data
    Ms points were shifted by -25 K to account for Gd depletion during patterning, which affects the comparison with TMC values.
assumptions (4)
  • domain assumption The 1D model of Thiaville et al. (ref. 17) describes SOT-driven DW dynamics and extends to ferrimagnets via effective parameters (Ms -> MRE - MTM, alpha -> alpha_eff).
    Used in Eqs. 1 and 2 and in the theoretical plots of Fig. 3; the interpretation of the Δv crossings relies on this model.
  • domain assumption The effective damping alpha_eff(T) diverges and changes sign at TAC, and the effective gyromagnetic ratio changes sign at TMC, as described by Hagedorn (ref. 25) and Stanciu/Binder (refs. 11, 12).
    This prior theoretical result is what the paper aims to test; if it were false, the assignment of T2 to TAC would not follow.
  • domain assumption The DW velocity is proportional to cos(phi) (Eq. 1), and an in-plane field HY affects phi only through a Zeeman torque on net Ms (Eq. 2).
    These relations underpin the claim that Δv changes sign at TMC and TAC.
  • ad hoc to paper Joule heating produces a single quadratic temperature shift T = TSP + a J^2 that is independent of HY and current polarity.
    This is fitted to the data and used to align all curves onto a common T axis. The two independent fits in Fig. 3c give the same a within 1 percent, but the Fig. 2c mobility peak fit gives a different value.

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Cite this review

Pith. "Pith review of Precession-free domain wall dynamics in compensated ferrimagnets." pith.science (2026). https://pith.science/paper/MDAJSW3F

@misc{pith2026190808867,
  author       = {Pith},
  title        = {Pith review of: Precession-free domain wall dynamics in compensated ferrimagnets},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/MDAJSW3F}},
  note         = {Machine review of arXiv:1908.08867}
}
read the original abstract

One fundamental obstacle to efficient ferromagnetic spintronics is magnetic precession, which intrinsically limits the dynamics of magnetic textures, We demonstrate that the domain wall precession fully vanishes with a record mobility when the net angular momentum is compensated (TAC) in DWs driven by spin-orbit torque in a ferrimagnetic GdFeCo/Pt track. We use transverse in-plane fields to reveal the internal structure of DWs and provide a robust and parameter-free measurement of TAC. Our results highlight the mechanism of faster and more efficient dynamics in materials with multiple spin lattices and reduced net angular momentum, promising for high-speed, low-power spintronics applications.

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Works this paper leans on

25 extracted references · 22 canonical work pages

  1. [1]

    Wadley, B

    P. Wadley, B. Howells, J. Elezny, C. Andrews, V. Hills, R. P. Campion, V. Novak, K. Olejnik, F. Maccherozzi, S. S. Dhesi, S. Y. Martin, T. Wagner, J. Wunderlich, F. Freimuth, Y. Mokrousov, J. Kune, J. S. Chauhan, M. J. Grzybowski, A. W. Rushforth, K. W. Edmonds, B. L. Gallagher, and T. Jungwirth, Science (80-. ). 351, 587 (2016)

    work page 2016

  2. [2]

    Haltz, R

    E. Haltz, R. Weil, J. Sampaio, A. Pointillon, O. Rousseau, K. March, N. Brun, Z. Li, E. Briand, C. Bachelet, Y. Dumont, and A. Mougin, Phys. Rev. Mater. 2, 104410 (2018)

    work page 2018

  3. [3]

    Haltz, J

    E. Haltz, J. Sampaio, R. Weil, Y. Dumont, and A. Mougin, Phys. Rev. B 99, 104413 (2019)

    work page 2019

  4. [4]

    S. A. Siddiqui, J. Han, J. T. Finley, C. A. Ross, and L. Liu, Phys. Rev. Lett. 121, 057701 (2018)

    2018

  5. [5]

    Caretta, M

    L. Caretta, M. Mann, F. Büttner, K. Ueda, B. Pfau, C. M. Günther, P. Hessing, A. Churikova, C. Klose, M. Schneider, D. Engel, C. Marcus, D. Bono, K. Bagschik, S. Eisebitt, and G. S. D. Beach, Nat. Nanotechnol. 13, 1154 (2018)

    work page 2018

  6. [6]

    K. Ueda, M. Mann, P. W. P. de Brouwer, D. Bono, and G. S. D. Beach, Phys. Rev. B 96, 064410 (2017)

    work page 2017

  7. [7]

    D. Bang, J. Yu, X. Qiu, Y. Wang, H. Awano, A. Manchon, and H. Yang, Phys. Rev. B 93, 174424 (2016)

    work page 2016

  8. [8]

    Bläsing, T

    R. Bläsing, T. Ma, S.-H. Yang, C. Garg, F. K. Dejene, A. T. N’Diaye, G. Chen, K. Liu, and S. S. P. Parkin, Nat. Commun. 9, 4984 (2018)

    work page 2018

Show all 25 references
  1. [9]

    Hansen, C

    P. Hansen, C. Clausen, G. Much, M. Rosenkranz, and K. Witter, J. Appl. Phys. 66, 756 (1989)

    1989

  2. [10]

    Jiang, L

    X. Jiang, L. Gao, J. Z. Sun, and S. S. P. Parkin, Phys. Rev. Lett. 97, 217202 (2006)

    2006

  3. [13]

    D.-H. Kim, T. Okuno, S. K. Kim, S.-H. Oh, T. Nishimura, Y. Hirata, Y. Futakawa, H. Yoshikawa, A. Tsukamoto, Y. Tserkovnyak, Y. Shiota, T. Moriyama, K.-J. Kim, K.-J. Lee, and T. Ono, Phys. Rev. Lett. 122, 127203 (2019)

    2019

  4. [14]

    Hirata, D.-H

    Y. Hirata, D.-H. Kim, S. K. Kim, D.-K. Lee, S.-H. Oh, D.-Y. Kim, T. Nishimura, T. Okuno, Y. Futakawa, H. Yoshikawa, A. Tsukamoto, Y. Tserkovnyak, Y. Shiota, T. Moriyama, S.-B. Choe, K.-J. Lee, and T. Ono, Nat. Nanotechnol. 14, 232 (2019). 7

    2019

  5. [15]

    K.-J. Kim, S. K. Kim, Y. Hirata, S.-H. Oh, T. Tono, D.-H. Kim, T. Okuno, W. S. Ham, S. Kim, G. Go, Y. Tserkovnyak, A. Tsukamoto, T. Moriyama, K.-J. Lee, and T. Ono, Nat. Mater. 16, 1187 (2017)

    2017

  6. [16]

    Hirata, D.-H

    Y. Hirata, D.-H. Kim, T. Okuno, T. Nishimura, Y. Futakawa, H. Yoshikawa, W. Ham, S. Kim, A. Tsukamoto, Y. Shiota, T. Moriyama, K.-J. Kim, and T. Ono, Appl. Phys. Express 11, 063001 (2018)

    2018

  7. [18]

    K.-S. Ryu, L. Thomas, S.-H. Yang, and S. Parkin, Nat. Nanotechnol. 8, 527 (2013)

    2013

  8. [19]

    Hayashi, J

    M. Hayashi, J. Kim, M. Yamanouchi, and H. Ohno, Phys. Rev. B 89, 144425 (2014)

    2014

  9. [20]

    Garello, I

    K. Garello, I. M. Miron, C. O. Avci, F. Freimuth, Y. Mokrousov, S. Blügel, S. Auffret, O. Boulle, G. Gaudin, and P. Gambardella, Nat. Nanotechnol. 8, 587 (2013)

    2013

  10. [21]

    I. M. Miron, T. Moore, H. Szambolics, L. D. Buda-Prejbeanu, S. Auffret, B. Rodmacq, S. Pizzini, J. Vogel, M. Bonfim, A. Schuhl, and G. Gaudin, Nat. Mater. 10, 419 (2011)

    2011

  11. [23]

    Ryu, S.-H

    K.-S. Ryu, S.-H. Yang, L. Thomas, and S. S. P. Parkin, Nat. Commun. 5, 3910 (2014)

    2014

  12. [24]

    Yang, K.-S

    S.-H. Yang, K.-S. Ryu, and S. Parkin, Nat. Nanotechnol. 10, 221 (2015)

    2015

  13. [25]

    Precession-free domain wall dynamics in compensated ferrimagnets

    F. B. Hagedorn, AIP Conf. Proc. 5, 72 (1972). 1 Supplementary materials to “Precession-free domain wall dynamics in compensated ferrimagnets” E. Haltz1, J. Sampaio1, S. Krishnia1, L. Berges1, R. Weil1 and A. Mougin1 1 Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud,...

    1972

  14. [26]

    Thiaville, S

    A. Thiaville, S. Rohart, E. Jué, V. Cros, and A. Fert, Europhys. Lett. 100, 57002 (2012)

    2012

  15. [27]

    F. B. Hagedorn, AIP Conf. Proc. 5, 72 (1972)

    1972

  16. [28]

    C. D. Stanciu, A. V. Kimel, F. Hansteen, A. Tsukamoto, A. Itoh, A. Kirilyuk, and T. Rasing, Phys. Rev. B 73, 220402 (2006)

    2006

  17. [29]

    Binder, A

    M. Binder, A. Weber, O. Mosendz, G. Woltersdorf, M. Izquierdo, I. Neudecker, J. Dahn, T. Hatchard, J.-U. Thiele, C. Back, and M. Scheinfein, Phys. Rev. B 74, 134404 (2006)

    2006

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