APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017;
New Orleans, Louisiana
Session S48: Frustrated Magnetism: Spin Liquids II
11:15 AM–2:15 PM,
Thursday, March 16, 2017
Room: 395
Sponsoring
Units:
GMAG DMP
Chair: Masaaki Matsuda, Oak Ridge National Lab
Abstract ID: BAPS.2017.MAR.S48.7
Abstract: S48.00007 : Quantum spin liquid and spin ice states in new pyrochlores.
12:27 PM–1:03 PM
Preview Abstract
Abstract
Author:
Romain Sibille
(Paul Scherrer Institut)
Magnetic systems with competing interactions can adopt exotic ground states.
A particularly promising class is that of the geometrically frustrated
magnets, such as the A$_{\mathrm{2}}$B$_{\mathrm{2}}$O$_{\mathrm{7}}$
pyrochlores, in which unusual spin liquids appear. Some of these phases
feature short-range correlated states analogous to a Coulomb phase and give
rise to emergent quasiparticle excitations. Although cases like the
classical spin ice are reasonably well understood, the theoretical
expectation is that quantum fluctuations lead to novel phases which are
quantum spin liquids (QSLs). For instance, the quantum spin ice (QSI) is a
generalization of the classical spin ice state to include quantum
fluctuations, such that the effective theory becomes emergent quantum
electrodynamics - the classical monopoles become coherent quantum
quasiparticles, and a novel excitation playing the role of the photon
appears. In this talk, I will present results on three novel materials with
potential for QSL states. Each of them corresponds to a way to potentially
strengthen the role of quantum fluctuations on the ground state properties
of pyrochlore magnets. Firstly, I will demonstrate that, in
Tb$_{\mathrm{2}}$Hf$_{\mathrm{2}}$O$_{\mathrm{7}}$, where a sizeable gap
isolates the non-Kramers ground state doublet at low temperature, a large
amount of anion Frenkel disorder leads to quenched random crystal fields and
disordered magnetic interactions. The detailed study of this material
demonstrates that disorder can play a crucial role in preventing long-range
magnetic order at low temperatures, and instead induces a
strongly-fluctuating Coulomb spin liquid with defect-induced frozen magnetic
degrees of freedom. Secondly, I will present results on another QSL
candidate based on non-Kramers ions,
Pr$_{\mathrm{2}}$Hf$_{\mathrm{2}}$O$_{\mathrm{7}}$, which displays striking
characteristics of the ferromagnetic correlations expected in a QSI.
Finally, in the pyrochlore
Ce$_{\mathrm{2}}$Sn$_{\mathrm{2}}$O$_{\mathrm{7}}$, where macroscopic
measurements suggest an antiferromagnetic liquid ground state with quantum
fluctuations, I will present results including the determination of the
crystal field states of the Kramers Ce$^{\mathrm{3+}}$ ions in order to
connect with recent theoretical proposals.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2017.MAR.S48.7