ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,
dec. 10. péntek 10h15,
hibrid formátum:

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba
és
online
<https://teams.microsoft.com/l/meetup-join/19%3ae1a26210676841cdbb27bb01cf353392%40thread.tacv2/1638986473731?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22c7eaf7d2-684b-4597-b217-6a9121400219%22%7d>
a Microsoft Teamsben

Yasir Iqbal (IIT Madras, Chennai, India):

Quantum Spin Liquid Physics on a novel square-kagome lattice material

The search for quantum spin liquids is one of the most hotly pursued
endeavors in condensed matter physics. In two dimensions, corner-sharing
triangular geometries such as the kagome lattice have proved to be a
fertile ground in realizing these exotic phases of quantum matter. In this
talk, I will discuss the novel square-kagome lattice geometry as an ideal
playground for realizing quantum spin liquids, being motivated by its
recent first of a kind experimental realization in the spin S=1/2 system
KCu6AlBiO4(SO4)5Cl. Towards understanding the rich quantum phase diagram of
the square-kagome lattice, we employ[1] state-of-the-art quantum many-body
numerical techniques such as variational Monte Carlo (VMC) with versatile
Gutzwiller-projected Jastrow wave functions, unconstrained multi-variable
variational Monte Carlo (mVMC), and pseudo-fermion/Majorana functional
renormalization group (PF/PM-FRG) methods. We establish the presence of a
quantum paramagnetic ground state and investigate its nature, by
classifying symmetric and chiral quantum spin liquids, and inspecting their
instabilities towards competing valence-bond-crystal (VBC) orders. Our VMC
analysis reveals that a VBC with a pinwheel structure emerges as the
lowest-energy variational ground state, and it is obtained as an
instability of the U(1) Dirac spin liquid. Analogous conclusions are drawn
from mVMC calculations employing accurate BCS pairing states supplemented
by symmetry projectors, which confirm the presence of pinwheel VBC order by
a thorough analysis of dimer-dimer correlation functions. Our work
highlights the nontrivial role of accounting for further neighbor
Heisenberg and/or Dzyaloshinkii-Moriya interactions towards explaining the
experimental observations.

[1]: arXiv:2110.08198 (2021), Pinwheel valence-bond-crystal ground state of
the spin-1/2 Heisenberg antiferromagnet on the shuriken lattice, N
Astrakhantsev, F Ferrari, N Niggemann, T Müller, A Chauhan, A Kshetrimayum,
P Ghosh, N Regnault, R Thomale, J Reuther, T Neupert, Y Iqbal

Minden érdeklődőt szeretettel várunk.

Asbóth János
szemináriumi koordinátor