Theory of SU(2) invariant spin liquids on the triangular lattice with spinful Majorana excitations
Theory of SU(2) invariant spin liquids on the triangular lattice with spinful Majorana excitations
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自旋马约拉纳激发三角晶格上SU(2)不变自旋液体理论
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
S. Sachdev
中科院分区：
文献类型：
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作者：
R. R. Biswas;L. Fu;C. Laumann;S. Sachdev
我们描述了一类新的自旋液体，它具有整体SU（2）自旋旋转对称性，在三角晶格上的自旋1/2系统中，它具有携带自旋S = 1的真实的Majorana费米子激发。三角晶格上最简单的对称不变平均场态打破了时间反演对称性，对涨落是稳定的。它一般具有沿布里渊区沿着3条费米线的无带隙激发。这些相交于一个点，在该点处激励以动态指数z = 3缩放。外磁场与SU（2）自旋旋转不变的费米子双线性没有轨道耦合，这会产生横向热导率，从而导致不存在热霍尔效应。发现塞曼耦合在交叉点附近间隔了z = 3激发的三分之二，这导致低温比热、自旋磁化率和威尔逊比的抑制。我们还计算弱无序的存在下的物理性质，并讨论可能的连接到最近的有机绝缘体的实验。
We describe a new class of spin liquids with global SU(2) spin rotation symmetry in spin 1/2 systems on the triangular lattice, which have real Majorana fermion excitations carrying spin S = 1. The simplest translationally-invariant mean-field state on the triangular lattice breaks time-reversal symmetry and is stable to fluctuations. It generically possesses gapless excitations along 3 Fermi lines in the Brillouin zone. These intersect at a single point where the excitations scale with a dynamic exponent z = 3. An external magnetic field has no orbital coupling to the SU(2) spin rotation-invariant fermion bilinears that can give rise to a transverse thermal conductivity, thus leading to the absence of a thermal Hall effect. The Zeeman coupling is found to gap out two-thirds of the z = 3 excitations near the intersection point and this leads to a suppression of the low temperature specific heat, the spin susceptibility and the Wilson ratio. We also compute physical properties in the presence of weak disorder and discuss possible connections to recent experiments on organic insulators.