Arxiv Selection Aug 2020

From Liu Group Arxiv Selection and Meeting Schedule
Jump to: navigation, search

Aug 1- Aug 7 Bhaskar Mukherjee, Aug 8- Aug 14 Zehan Li, Aug 15- Aug 21 Haiping Hu, Aug 22- Aug 28 Sayan Choudhury


Aug 10

arXiv:2008.03476 [pdf, ps, other]

Duality in quantum transport models

Rouven Frassek, Cristian Giardina', Jorge Kurchan

Comments: 8 pages

Subjects: Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph); Probability (math.PR); Quantum Physics (quant-ph)

We develop the `duality approach', that has been extensively studied for classical models of transport, for quantum systems in contact with a thermal `Lindbladian' bath. The method provides (a) a mapping of the original model to a simpler one, containing only a few particles and (b) shows that any dynamic process of this kind with generic baths may be mapped onto one with equilibrium baths. We exemplify this through the study of a particular model: the quantum symmetric exclusion process introduced in [D. Bernard, T. Jin, Phys. Rev. Lett. 123, 080601 (2019)]. As in the classical case, the whole construction becomes intelligible by considering the dynamical symmetries of the problem.


Aug 11

arXiv:2008.03743 [pdf, other]

Magnetic Order and Competition With Superconductivity in (Er-Ho)Ni2B2C

Suleyman Gundogdu, J. Patrick Clancy, Guangyong Xu, Yang Zhao, Paul A. Dube, Tufan C. Karalar, Beong Ki Cho, Jeffrey W. Lynn, M. Ramazanoglu

Comments: 8 pages, 4 figures , Research Article

Subjects: Superconductivity (cond-mat.supr-con); Strongly Correlated Electrons (cond-mat.str-el)

The rare earth magnetic order in pure and doped Er(1−x)HoxNi2B2C (x~=~0,~0.25,~0.50,~0.75,~1) single crystal samples was investigated using magnetization and neutron diffraction measurements. Superconducting quaternary borocarbides, RNi2B2C where R~=~Er, Ho , are both magnetic intermetallic superconductors with the transition temperatures ∼ 10 K. These compounds also develop magnetic order in the vicinity of this temperature. Depending on the rare earth composition the coupling between superconductivity and magnetism creates several phases, ranging from a reentrant superconductor with a mixture of commensurate and incommensurate antiferromagnetism to a total incommensurate antiferromagnetic spin modulation with a weak ferromagnetic state. All of these phases coexist with superconductivity. RKKY magnetic interactions are used to describe the magnetic orders in the pure compounds. However, the doping of Ho on Er (or Er on Ho) sites which have two strong magnetic moments with two different easy directions creates new and complicated magnetic modulations with possible local disorder effects. One fascinating effect is the development of an induced magnetic state resembling the pure and doped R2CuO4, R~=~Nd and Pr.


Aug 12

arXiv:2008.03748 [pdf, other]

Chiral p-wave superconductivity in twisted bilayer graphene from dynamical mean field theory

B. Pahlevanzadeh, P. Sahebsara, D. Sénéchal

We apply cluster dynamical mean field theory with an exact-diagonalization impurity solver to a Hubbard model for magic-angle twisted bilayer graphene, built on the tight-binding model proposed by Kang and Vafek [1]. This model applies to the magic angle 1.30◦. We find that triplet superconductivity with p + ip symmetry is stabilized by CDMFT, contrary to other triplet or singlet order parameters. A minimum of the order parameter exists close to quarter-filling, as observed in experiments.


Aug 13

arXiv:2008.03956 [pdf]

Pseudospin-mediated Atomic-scale Vortices and Their Quantum Interferences in Monolayer Graphene

Yu Zhang, Lin He

Comments: 4 figures in main text

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Vortex is a universal and significant phenomenon that has been known for centuries. However, creating vortices to the atomic limit has remained elusive because that the characteristic length to support a vortex is usually much larger than the atomic scale. Here, we demonstrate that pseudospin in graphene can help us to overcome this limitation and a single carbon defect in monolayer graphene is a pseudospin-mediated atomic-scale vortex. Using a plane wave to interfere with the vortex, we can obtain wavefront dislocations that directly reflect its topological and chiral features. In our experiments, N = 2 and -2 additional wavefronts are observed for the single carbon defects at A and B sublattices of graphene, demonstrating that they are atomic-scale vortices with angular momenta l = 2 and -2, respectively. Quantum interferences of two atomic-scale vortices with the same (or opposite) angular momentum are systematically studied with respect to their distances. Our result highlights the way to tailor the atomic-scale vortex in systems with pseudospin degree of freedom.


Aug 14

arXiv:2008.04346 [pdf, other]

Optically induced topological superconductivity via Floquet interaction engineering

Hossein Dehghani, Mohammad Hafezi, Pouyan Ghaemi

Comments: 14 pages, 3 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)

We study the photo-induced superconductivity in a two-valley semiconductor with a massive Dirac type band structure. The superconducting phase results from the out-of-equilibrium excitation of carriers in the presence of Coulomb repulsion and is stabilized by coupling the driven semiconductor to a bosonic or fermionic thermal bath. We consider a circularly-polarized light pump and show that by controlling the detuning of the pump frequency relative to the band gap, different types of chiral superconductivity would be induced. The emergence of novel superconducting states, such as the chiral p-wave pairing, results from the Floquet engineering of the interaction. This is realized by modifying the form of the Coulomb interaction by projecting it into the states that are resonant with the pump frequency. We discuss a promising experimental platform to realize our proposal.