Giant anisotropy of magnetocaloric effect in TbMnO3 single crystals

The magnetocaloric effect (MCE) in TbMnO3 single crystals was investigated by isothermal magnetization curves for the ab plane at low temperatures. Large magnetic entropy change, Delta S-M = -18.0 J/kg K, and the refrigerant capacity, RC = 390.7 J/kg, are achieved near the ordering temperature of Tb3+ moment (T-N(Tb)) under 70 kOe along the a axis. Furthermore, the TbMnO3 single crystal exhibits a giant MCE anisotropy. The difference of Delta S-M and RC between the a and b axes is field and temperature dependent, which reaches maximum values of 11.4 J/kg K and 304.1 J/kg, respectively. By taking magnetocrystalline anisotropy into account, the rotating Delta S-M within the ab plane can be well simulated, indicating that the anisotropy of Delta S-M is directly contributed from the magnetocrystalline anisotropy. Our finding for giant MCE anisotropy in TbMnO3 single crystals explores the possibility of using this material for magnetic refrigerators by rotating its magnetization vector rather than moving it in and out of the magnet.