Sándor Bordács is an associate professor at the BME. On one hand his research focuses on the optical properties of magnets, that he studies by THz, infrared and visible spectroscopy. He demonstrated that non-centrosymmetric magnets can absorb the light for one propagation direction whereas they are transparent when the light propagation is reversed. Since the transparent and absorbing directions can be reversed by external magnetic and electric fields, this phenomenon can find applications in switchable diodes for light. Since 2015, he has been studying the whirling patterns of spins, the so-called magnetic skyrmions and spin spirals. With his colleagues he discovered Néel-type magnetic skyrmions in bulk polar magnets, and showed that these skyrmions can possess a complex electric polarization pattern as well. He has been awarded the Premium Postdoctoral grant of the MTA, Bolyai medal and the Junior Prima prize.

Selected publications:

Magnetic Field Control of Cycloidal Domains and Electric Polarization in Multiferroic BiFeO3
S. Bordács, D.G. Farkas, J.S. White, R. Cubitt, L. DeBeer-Schmitt, T. Ito, and I. Kézsmárki
Physical Review Letters 120, 147203 (2018)

Equilibrium Skyrmion Lattice Ground State in a Polar Easy-plane Magnet
S. Bordács, Á. Butykai, B.G. Szigeti, J.S. White, R. Cubitt, A.O. Leonov, S. Widmann, D. Ehlers, H.A. von Nidda, V. Tsurkan, A. Loidl, and I. Kézsmárki
Scientific Reports 7, 7584 (2017)

Néel-type Skyrmion Lattice with Confined Orientation in the Polar Magnetic Semiconductor GaV4S8
I. Kézsmárki, S. Bordács, P. Milde, E. Neuber, L.M. Eng, J.S. White, H.M. Rønnow, C.D. Dewhurst, M. Mochizuki, K. Yanai, H. Nakamura, D. Ehlers, V. Tsurkan, and A. Loidl
Nature Materials 14, 1116 (2015)

Landau Level Spectroscopy of Dirac Electrons in a Polar Semiconductor with Giant Rashba Spin Splitting
S. Bordács, J.G. Checkelsky, H. Murakawa, H.Y. Hwang, and Y. Tokura
Physical Review Letters 111, 166403 (2013)

Chirality of matter shows up via spin excitations
S. Bordács, I. Kézsmárki, D. Szaller, L. Demkó, N. Kida, H. Murakawa, Y. Onose, R. Shimano, T. Rõõm, U. Nagel, S. Miyahara, N. Furukawa, and Y. Tokura
Nature Physics 8, 734 (2012)

Magnetic-order-induced crystal symmetry lowering in ACr2O4 ferrimagnetic spinels
S. Bordács, D. Varjas, I. Kézsmárki, G. Mihály, L. Baldassarre, A. Abouelsayed, C.A. Kuntscher, K. Ohgushi, and Y. Tokura
Physical Review Letters 103, 077205 (2009)