# Seminar: “Magnetic vortex crystals in frustrated Mott insulator” Dr. Yoshitomo Kamiya Los Alamos, National Laboratory

### Date

Friday, April 5, 2013 - 11:00 to 12:00

### Location

D014, Lab 1, Campus

### Description

Theory of Quantum Matter (Nic. Shannon) Unit would like to invite you to a semiar presented by Dr. Yoshitomo Kamiya, Los Alamos National Laboratory:

Date: Friday 5th April

Time: 11:00am-12:00pm

Venue: D014, Lab 1, Campus

Speaker: Dr. Yoshitomo Kamiya, Theoretical Division, T-4 and CNLS, Los Alamos National Laboratory

Title: “Magnetic vortex crystals in frustrated Mott insulator”

Abstract:

Materials that exhibit topological spin textures are attracting enormous interest because of their potential for spintronics [1-3]. Competition between Dzyaloshinskii-Moriya and ferromagnetic exchange interactions leads to skyrmion lattices in a class of materials that share a common crystal structure. This includes insulators, like Cu$_2$OSeO$_3$, that allow for energetically efficient manipulation of the magnetic textures with electric field gradients [2]. Here we propose a novel mechanism for the stabilization of magnetic vortex crystals in frustrated Mott insulators that enables tunable spin superstructures [4]. By modeling the frustrated quantum magnet Ba$_3$Mn$_2$O$_8$ [5] near its magnetic field-induced quantum critical point, we show that the quantum phase diagram includes novel magnetic vortex crystals, whose lattice parameter is controlled by the ratio between inter and intra-layer exchange. This property opens the attractive possibility of tuning the vortex density by applying pressure.

References:

[1] S. Mühlbauer et al., Science 323, 915 (2009); W. Münzer et al., PRB 81, 041203 (2010); X. Z. Yu et al., Nature 465, 901 (2010); X. Z. Yu et al., Nat. Mater. 10, 106 (2011)

[2] S. Seki et al., Science 336, 198 (2012); Y. Onose et al., PRL 109, 037603 (2012)

[3] T. Okubo, S. Chung, and H. Kawamura, PRL 108, 017206 (2012)

[4] YK and C. D. Batista, arXiv:1303.0012 (unpublished)

[5] M. Uchida et al., PRB 66, 054429 (2002)