Conveners
TS-8 Magnetic North VII / Nord magnétique VII
- Bruce Gaulin (McMaster University)
MBT for TBM (Topological Band Magnetism)
A.H. MacDonald, C. Lei, Shu Chen, O. Heinonen, and R.J. McQueeney
Physics Department, University of Texas at Austin 78712 USA
Bulk MnBi2Te4 and MnBi2Se4 are antiferromagnetic topological insulators [1], and also van der Waals compounds with weakly-coupled seven-atom-thick (septuple) layers. I will discuss the electronic, magnetic, and topological...
We report the observation of a giant c-axis nonlinear anomalous Hall effect in the non-centrosymmetric Td phase of MoTe2 without intrinsic magnetic order. Here, application of an in-plane current generates a Hall field perpendicular to the layers. By measuring samples across different thicknesses and temperatures, we find that the nonlinear susceptibility obeys a universal scaling with sample...
Magnetic atoms on superconductors induce an exchange coupling, which leads to states within the superconducting energy gap. These so-called Yu-Shiba-Rusinov (YSR) states can be probed by scanning tunneling spectroscopy at the atomic scale. Here, we investigate single magnetic adatoms on a superconducting Pb surface.
As YSR states are within the superconducting energy gap, their excitation by...
Majorana bound states are zero-energy states predicted to emerge in topological superconductors and intense efforts seeking a definitive proof of their observation are still ongoing. A standard route to realize them involves antagonistic orders: a superconductor in proximity to a ferromagnet. Here, we show that this issue can be resolved using antiferromagnetic rather than ferromagnetic order....
Level attraction describes a mode coalescence that can take place in driven open systems. It indicates a development of an instability region in the energy spectrum of the system bounded by exceptional points [1]. This regime has been recently reported in a number of experiments in driven dissipative cavity magnonic systems [2].
Here, we present a framework for describing the mode...
Elementary excitations in highly entangled states such as quantum spin liquids may exhibit exotic statistics, different from those obeyed by fundamental bosons and fermions. Excitations called non-Abelian anyons are predicted to exist in a Kitaev spin liquid - the ground state of an exactly solvable model proposed by Kitaev. Material realization of the spin liquid has been the subject of...
$\mathrm{Mn}_3\mathrm{X}$ compounds in which the magnetic $\mathrm{Mn}$ atoms form AB-stacked kagome lattices have received a tremendous amount of attention since the observation of the anomalous Hall effect in $\mathrm{Mn}_3\mathrm{Ge}$ and $\mathrm{Mn}_3\mathrm{Sn}$. Although the magnetic ground state has been known for some time to be an inverse triangular structure with an induced in-plane...
The Ce3+ pseudospin-1/2 degrees of freedom in the pyrochlore magnet Ce2Zr2O7 are known to possess dipole-octupole (DO) character, making it a candidate for novel quantum spin liquid (QSL) ground states at low temperatures. We report new heat capacity (CP) measurements on Ce2Zr2O7, which can be extrapolated to zero temperature to account for R·ln(2) entropy using a form appropriate to quantum...
The physics of heavy 5d transition metal oxides can be remarkably different from that of their lighter 3d counterparts. In particular, the presence of strong spin-orbit coupling (SOC) effects can lead to the formation of exotic ground states such as spin-orbital Mott insulators, topological insulators, Weyl semimetals, and quantum spin liquids. In materials with an edge-sharing octahedral...
We study an effective pseudo-spin model from microscopics for d$^2$ materials on various lattice geometries. It was found that the interplay between electron-electron interactions and spin-orbit coupling generates intriguing multipole-multipole interactions. These interactions give rise to various multipolar phases, which were identified using computational techniques such as classical Monte...
Condensed matter systems admit topological collective excitations above a trivial ground state, an example being Chern insulators formed by Dirac bosons with a gap at finite energies. However, in contrast to electrons, there is no particle-number conservation law for collective excitations. This gives rise to particle number-nonconserving many-body interactions whose influence on...
We argue that the usual magnetization $\vec{M}$, which represents a correlated property of 10$^{23}$ variables, but is summarized by a single variable, cannot diffuse; only the non-equilibrium spin accumulation magnetization $\vec{m}$, due to excitations, can diffuse. For transverse deviations from equilibrium this is consistent with work by Silsbee, Janossy, and Monod (1979), and by...
