Abstrakt
Spin relaxation and a magnetocaloric effect in a dipolar spin ice Pr2Sn2O7 were investigated by magnetization and alternating susceptibility measurements in Kelvin temperature range and magnetic fields exceeding the estimated value of the saturation field B-sat. An analysis of AC susceptibility revealed existence of two relaxation channels.
The calculation of energy spectrum of a single tetrahedron suggests that a fast temperature independent relaxation may be associated with a cross-tunneling process, in which four spins in one tetrahedron are involved. In contrast, a slow relaxation is attributed to a phonon-bottleneck effect.
A particle-size analysis identifies a phonon scattering in grain boundaries as a governing mechanism of the phonon bottleneck. Systematic measurements of the magnetization were performed to study magnetocaloric effect in Pr2Sn2O7.
A complex analysis of the isothermal change of magnetic entropy Delta S-m revealed a dominating effect of magnetocrystalline anisotropy on a magnetocaloric response in an Ising-spin system with a high level of geometrical frustration. The origin of the observed behavior is discussed. (C) 2019 Elsevier B.V.
All rights reserved.