Quantum and Classical Glass Transitions inLiHoxY1−xF4

Abstract

When performed in the proper low-field, low-frequency limits, measurements of the dynamics and the nonlinear susceptibility in the model Ising magnet in a transverse field LiHo(x)Y(1-x)F(4) prove the existence of a spin-glass transition for x=0.167 and 0.198. The classical behavior tracks for the two concentrations, but the behavior in the quantum regime at large transverse fields differs because of the competing effects of quantum entanglement and random fields.

Suppression of ferromagnetism in the La(VxCr1−x)Sb3system

“…If T 1 is used as a criterion for determining the transition to a low-temperature magnetic state for the whole series, it seems that the magnetic transition temperature gets gradually suppressed by V substitution and drops below our base-temperature of 2.0 K. If T 2 is used as the criterion for higher V-doped samples, then considering the features observed in M (H), M (T )/H and ρ(T ) for x = 0.33 and 0.36, it seems that x = 0.33 -0.36 is a region for the system to transition from the ferromagnetic state to a new magnetic state. Similar phenomena have also been observed in the LiHo x Y 1−x F 4 family: for 0.25 ≤ x ≤ 0.5, the system is claimed to be in a "ferroglass" regime, where spin glass and ferromagnetic phase coexist [37,38]. In fig.…”

Collective Phenomena in the LiHoxY1−xF4Quantum Ising Magnet: Recent Progress and Open Questions

“…These results prompted Jönsson et al to conclude that there is no thermodynamic spin glass phase at all in the compound. In response to this work, Ancona-Torres et al re-examined the non-linear susceptibility for x = 16.7% and x = 19.8% and concluded that χ 3 does diverge [51]. A possible explanation put forward in Ref.…”

“…1). We note that there has been much debate as to whether such a spin glass phase occurs for x 0.25 in LiHo x Y 1−x F 4 [51,52,53]. We proceed in this section with the assumption that a thermodynamic spin glass phase does exist, at least for 0.15 x 0.25.…”

“…A possible explanation put forward in Ref. [51] for the discrepancy between the works of Ref. [52] and Ref.…”

“…This means that, in comparison with the energy scale for FM order that determines the classical transition at T c (B x = 0, x), B x becomes more efficient at destroying FM order the lower the concentration x is [59]. Secondly, for B x = 0, LiHo 0.167 Y 0.833 F 4 has generally been believed to exhibit a conventional spin glass (SG) transition [51] (see however Ref. [52,53]), with the transition signaled by a nonlinear magnetic susceptibility, χ 3 , diverging at T g as χ 3 (T ) ∝ (T − T g ) −γ [48].…”