Dimensionality and irreversibility of field-induced transitions in SrDy2O4

Low temperature ultrasound velocity measurements are presented on the frustrated spin system SrDy2O4 that allow us to define high resolution phase diagrams with the magnetic field applied along all three principal axes. For H||b, a region of field-induced long range order is delimited by a dome of first-order phase transitions. An unusual magnetization process is observed with significant irreversibility at very low temperatures when passing between the low-field spin liquid phase and the long range ordered phase which we attribute to large energy barriers. For H||c, the system appears to remain effectively one-dimensional, exhibiting two transitions as a function of magnetic field, but no finite-temperature long range order.