Abstract
We have shown the equivalence, at low energies, of dilute anisotropic
dipolar magnets to the Ising model in the presence of an effective
random longitudinal field and an effective transverse field, both of
which are independently tunable. In the ferromagnetic (FM) regime [1],
these systems constitute the first realization of the classical, as well
as quantum, random field Ising model in a FM system, allowing, in
particular, the application of a longitudinal field conjugate to the FM
order parameter. In the spin-glass regime [2,3] we elucidate the role of
both the hyperfine interactions, which couple the system to a spin bath
and change the low-energy degrees of freedom, and the off-diagonal terms
of the dipolar interactions, which lead to the effective random field.
This resolves long standing questions regarding quantum spin glasses in
general, and the quantum phase transition between the spin glass and
paramagnetic phases in particular. [1]
LiHoxY1-xF4 as a random field Ising
ferromagnet, M. Schechter, Cond-mat/0611063. [2] Significance of
the hyperfine interactions in the phase diagram of
LiHoxY1-xF4, M. Schechter and P. C. E.
Stamp, Phys. Rev. Lett. 95, 267208 (2005). [3] Quantum spin glass
and the dipolar interactions, M. Schechter and N. Laflorencie, Phys.
Rev. Lett. 97, 137204 (2006).
Original language | English |
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Title of host publication | American Physical Society, 2008 APS March Meeting, March 10-14, 2008 |
State | Published - 1 Mar 2008 |