相关论文: On Spin 1/2 Excitations and Quantum Criticality in…
It has been proposed that there are new degrees of freedom intrinsic to quantum critical points that contribute to quantum critical physics. We study 2+1 D antiferromagnets in order to explore possible new quantum critical physics arising…
It has been proposed that there are degrees of freedom intrinsic to quantum critical points that can contribute to quantum critical physics. We point out that this conclusion is quite general below the upper critical dimension. We show that…
The Neel magnetization of 2+1 D antiferromagnets is composed of quark-like spin 1/2 constituents, the spinons, as follows from the CP^1 mapping. These quark spinons are confined in both the Neel ordered phase and quantum paramagnetic…
The familiar spin-1/2 quantum Heisenberg antiferromanget in a 2d square lattice is shown, within the non linear sigma model approximations, to be another novel state of matter that has excitations with fractional quantum numbers above a…
The free fermion nature of interacting spins in one dimensional (1D) spin chains still lacks a rigorous study. In this letter we show that the length-$1$ spin strings significantly dominate critical properties of spinons, magnons and free…
We propose an effective theory for the critical phase of a quantum ferrimagnetic chain with alternating spins 1 and 1/2 in an external magnetic field. With the help of the matrix product variational approach, the system is mapped to a…
We present the quantum critical theory of an interacting nodal Fermi-liquid of quasi-relativisitc pseudo-spin-3/2 fermions that have a non-interacting birefringent spectrum with two distinct Fermi velocities. When such quasiparticles…
We study the quantum mechanics of magnetic skyrmions in the vicinity of the skyrmion-crystal to ferromagnet phase boundary in two-dimensional magnets. We show that the skyrmion excitation has an energy dispersion that splits into multiple…
Spin excitations in an ordered Heisenberg magnet are magnons--bosons with spin 1. That may change when frustration and quantum fluctuations suppress the order and restore the spin-rotation symmetry. We show that spin excitations in the…
Deconfined quantum criticality of two-dimensional $SU(2)$ quantum antiferromagnets featuring a transition from an antiferromagnetically ordered ground state to a so-called valence-bond solid state, is governed by a non-compact CP$^1$ model…
Using 2D quantum spin-1/2 model as a concrete example, we studied the relation between gapless fermionic excitations (spinons) and quantum orders in some spin liquid states. Using winding number, we find the projective symmetry group that…
We report a new kagome quantum spin liquid candidate Cu$_3$Zn(OH)$_6$FBr, which does not experience any phase transition down to 50 mK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature ($\sim$ 200 K). A clear…
Quantum criticality describes the collective fluctuations of matter undergoing a second-order phase transition at zero temperature. It is being discussed in a number of strongly correlated electron systems. A prototype case occurs in the…
Kinetic properties of a two dimensional model of fermions interacting with antiferromagnetic spin excitations near the quantum critical point (QCP) are considered. The temperature or doping are assumed to be sufficiently high, such that the…
We report spontaneous appearance of antiferromagnetic order in a model gapped quantum paramagnet Ni(Cl$_{1-x}$Br$_x$)$_2$$\cdot$4SC(NH$_2$)$_2$ induced by a change in bromine concentration x. This transition is qualitatively similar to a z…
We revisit two-dimensional frustrated quantum magnetism from a new perspective, with the aim of exploring new critical points and critical phases. We study easy-plane triangular antiferromagnets using a dual vortex approach, fermionizing…
The impact of the non-2-spinon excitations of the one-dimensional $S=1/2$ Heisenberg antiferromagnet on the integrated intensity, the susceptibility, the frequency moments, and the Euclidian time representation of the $T=0$ dynamic spin…
Two-dimensional semi-Dirac fermions are quasiparticles that disperse linearly in one direction and quadratically in the other. We investigate instabilities of semi-Dirac fermions towards charge, spin-density wave and superconducting orders,…
A novel approach to S =1/2 antiferromagnets with strong fluctuations based on the representation of spin-1/2 operators as bylinear forms of real (Majorana) fermions is suggested. This representation has the advantage of being irreducible…
We study the level structure of excitations at the "deconfined" critical point separating antiferromagnetic and valence-bond-solid phases in two-dimensional quantum spin systems using the $J$-$Q$ model as an example. Energy gaps in…