S=1/2 quantum critical spin ladders produced by orbital ordering in Ba2CuTeO6

Abstract

The ordered hexagonal perovskite Ba2CuTeO6 hosts weakly coupled S=1/2 spin ladders produced by an orbital ordering of Cu2+. The magnetic susceptibility chi(T) of Ba2CuTeO6 is well described by that expected for isolated spin ladders with exchange coupling of J~86 K but shows a deviation from the expected thermally activated behavior at low temperatures below T*~25 K. An anomaly in chi(T), indicative of magnetic ordering, is observed at T_mag=16 K. No clear signature of long-range ordering, however, is captured in NMR, specific heat or neutron diffraction measurements at and below T_mag. The marginal magnetic transition, indicative of strong quantum fluctuations, is evidence that Ba2CuTeO6 is in very close proximity to a quantum critical point between a magnetically ordered phase and a gapped spin liquid controlled by inter-ladder couplings.

5 pages, 4 figures. Supplemental material included as an ancillary file

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Cited by in corpus (3)

• Quantum criticality in the coupled two-leg spin ladder Ba2CuTeO6
• Spin dynamics of coupled spin ladders near quantum criticality in Ba2CuTeO6
• Site-selective $d^{10}$/$d^0$ substitution in a $S=1/2$ spin ladder Ba${}_2$CuTe${}_{1-x}$W${}_x$O${}_6$ ($0\le x\le 0.3$)