Ultralow-temperature heat transport in the quantum spin liquid candidate Ca10Cr7O28 with a bilayer kagome lattice

Abstract

Recently, a novel material with bilayer kagome lattice Ca10Cr7O28 was proposed to be a gapless quantum spin liquid, due to the lack of long-range magnetic order and the observation of broad diffuse excitations. Here, we present the ultralow-temperature thermal conductivity measurements on single crystals of Ca10Cr7O28 to detect its low-lying magnetic excitations. At finite temperatures, with increasing the magnetic fields, the thermal conductivity exhibits a clear dip around 6 T, which may correspond to a crossover in the magnetic ground state. At the zero-temperature limit, no residual linear term is found at any fields, indicating the absence of gapless itinerant fermionic excitations. Therefore, if the spinons do exist, they are either localized or gapped. In the gapped case, the fitting of our data gives a small gap ∆ ∼ 0.27(2) K. These results put strong constraints on the theoretical description of the ground state in this quantum spin liquid candidate. arXiv:1803.03515v1 [cond-mat.str-el]

Possible itinerant excitations and quantum spin state transitions in the effective spin-1/2 triangular-lattice antiferromagnet Na2BaCo(PO4)2

“…For another QSL candidate pyrochlore Tb 2 Ti 2 O 7 , a saturated value of κ/T at 0.3 K was reported which resembles that of a dirty metal 24 . For other oxides, such as YbMgGaO 4 25 , another TAF with effective spin-1/2 Yb 3+ ions, and Ca 10 Cr 7 O 28 with bilayer kagome lattice 26 , the reported κ 0 /T term tends to be zero upon approaching zero temperature. This behavior could be closely related to the chemical disorder in both cases.…”

Thermal transport for probing quantum materials

“…Given the many excellent reviews available (30,53,54,(69)(70)(71) and the rapidly growing literature even restricted to thermal properties (44,65,(72)(73)(74)(75)(76)(77)(78)(79)(80)(81)(82)(83)(84), it is hard to summarize even a small portion of the active field of QSL; however, the critical importance of thermal transport is not hard to appreciate: the hallmark signature of a QSL state is a fractionalized gapless elementary excitation, called the spinon, which can be directly observed from thermal transport (Figure 2b). In the current context, "gap" means the energy gap between the ground state and the 1 st excited state in the many-body materials system.…”

Magnetic properties and magnetic structure of the frustrated quasi-one-dimensional antiferromagnet SrCuTe$_2$O$_6$

“…In recent years, significant progress has been made in the search, and many possible realizations of the quantum spin liquid were discovered and exhaustively studied 14 . A group of triangular-based materials that show quantum-spinliquid traits includes ZnCu 3 (OH) 6 Cl 2 [15][16][17] , Na 4 Ir 3 O 8 18 , YbMgGaO 4 19,20 , Ca 10 Cr 7 O 28 21,22 , Ce 2 Zr 2 O 7 23 , and PbCuTe 2 O 6 (Cu 2+ , S = 1/2) 24,25 .…”