Spin jam induced by quantum fluctuations in a frustrated magnet.
Since the discovery of spin glasses in dilute magnetic systems, their study has been largely focused on understanding randomness and defects as the driving mechanism. The same paradigm has also been applied to explain glassy states found in dense frustrated systems. Recently, however, it has been theoretically suggested that different mechanisms, such as quantum fluctuations and topological features, may induce glassy states in defect-free spin systems, far from the conventional dilute limit. Here we report experimental evidence for existence of a glassy state, which we call a spin jam, in the vicinity of the clean limit of a frustrated magnet, which is insensitive to a low concentration of defects. We have studied the effect of impurities on SrCr9pGa12-9pO19 [SCGO(p)], a highly frustrated magnet, in which the magnetic Cr(3+) (s = 3/2) ions form a quasi-2D triangular system of bipyramids. Our experimental data show that as the nonmagnetic Ga(3+) impurity concentration is changed, there are two distinct phases of glassiness: an exotic glassy state, which we call a spin jam, for the high magnetic concentration region (p > 0.8) and a cluster spin glass for lower magnetic concentration (p < 0.8). This observation indicates that a spin jam is a unique vantage point from which the class of glassy states of dense frustrated magnets can be understood.
Department of Physics, University of Virginia, Charlottesville, VA 22904;
Junjie
J
Yang
Department of Physics, University of Virginia, Charlottesville, VA 22904;
Anjana
A
Samarakoon
Department of Physics, University of Virginia, Charlottesville, VA 22904;
Sachith
S
Dissanayake
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan;
Hiroaki
H
Ueda
Department of Physics, University of Virginia, Charlottesville, VA 22904;
Israel
I
Klich
Research Center for Neutron Science and Technology, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan;
Kazuki
K
Iida
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Daniel
D
Pajerowski
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Nicholas P
NP
Butch
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Q
Q
Huang
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899.
John R D
JR
Copley
Department of Physics, University of Virginia, Charlottesville, VA 22904; shlee@virginia.edu.
Seung-Hun
SH
Lee
frustration; glassy states; spin jam