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Possible spin-orbit driven spin-liquid ground state in the double perovskite phase of Ba3YIr2O9

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Title Possible spin-orbit driven spin-liquid ground state in the double perovskite phase of Ba3YIr2O9
 
Creator DEY, T
MAHAJAN, AV
KUMAR, R
KOTESWARARAO, B
CHOU, FC
OMRANI, AA
RONNOW, HM
 
Subject TRANSITION
SR2IRO4
LA
 
Description We report the structural transformation of hexagonal Ba3YIr2O9 to a cubic double perovskite form (stable in ambient conditions) under an applied pressure of 8 GPa at 1273 K. While the ambient pressure synthesized sample undergoes long-range magnetic ordering at similar to 4 K, the high-pressure (HP) synthesized sample does not order down to 2 K as evidenced from our susceptibility, heat capacity, and nuclear magnetic resonance (NMR) measurements. Further, for the HP sample, our heat capacity data have the form gamma T + beta T-3 in the temperature (T) range of 2-10 K with the Sommerfeld coefficient gamma = 10 mJ/mol-Ir K-2. The Y-89 NMR shift has no T dependence in the range of 4-120 K and its spin-lattice relaxation rate varies linearly with T in the range of 8-45 K (above which it is T independent). Resistance measurements of both the samples confirm that they are semiconducting. Our data provide evidence for the formation of a 5d-based, gapless, quantum spin-liquid in the cubic (HP) phase of Ba3YIr2O9. In this picture, the gamma T term in the heat capacity and the linear variation of Y-89 1/T-1 arises from excitations out of a spinon Fermi surface. Our findings lend credence to the theoretical suggestion [Chen, Pereira, and Balents, Phys. Rev. B 82, 174440 (2010)] that strong spin-orbit coupling can enhance quantum fluctuations and lead to a QSL state in the double perovskite lattice.
 
Publisher AMER PHYSICAL SOC
 
Date 2014-10-16T14:31:41Z
2014-10-16T14:31:41Z
2013
 
Type Article
 
Identifier PHYSICAL REVIEW B, 88(13)
1098-0121
1550-235X
http://dx.doi.org/10.1103/PhysRevB.88.134425
http://dspace.library.iitb.ac.in/jspui/handle/100/15791
 
Language en