Quantum Technologies And Materials Laboratory (QuTM)

Most of the materials used in today’s technologies have properties that are relatively unaffected by electron interactions. Aluminum, diamond or even graphene are materials that may be reasonably explained within the non-interacting electrons model. However, when the interactions between electrons, spins, charges and orbitals become important, novels and fascinating physical phenomena emerge. Such materials are usually named correlated electron systems, and their understanding and possible implementation in future devices, are one of the great challenges of condensed matter physics. 

Our interest is to understand why and how unconventional phenomena arise, and how they can be optimized for technological applications. We are st​udying various types of correlated systems ranging from metal-to-insulator transition, superconductors, topological insulator or magnetic materials. We are investigating their electronic and magnetic properties using a combination of X-ray, neutron and muon techniques at large scale facilities all over the world. In principal, the electronic properties are studied using angle-resolved photoelectron spectroscopy (ARPES) and resonant X-ray scattering (RIXS), while the magnetic properties are probed with elastic/inelastic neutron scattering (ENS/INS) and muon spin rotation (µ+SR). We also synthesize organometallic compounds and thin-film deposition to study quantum magnetism and interface effects.  Our experimental results are combined with theoretical models performed in collaboration with the Materials Theory group in Uppsala University and Nordita.


Selected Publications

Magnetic phase diagram of K2Cr8O16 clarified by high-pressure muon spin spectroscopy

Ola Kenji Forslund, Daniel Andreica, Yasmine Sassa, Hiroshi Nozaki, Izumi Umegaki, Elisabetta Nocerino, Viktor Jonsson, Oscar Tjernberg, Zurab Guguchia, Zurab Shermadini, Rustem Khasanov, Masahiko Isobe, Hidenori Takagi, Yutaka Ueda, Jun Sugiyama, and Martin Mansson

Scientific Reports volume 9, 1141 (2019)

Direct observation of orbital hybridisation in a cuprate superconductor
C.E. Matt, D. Sutter, A. M. Cook, Y. Sassa, M. Mansson, O. Tjernberg, L. Das, M. Shi, V. Strocov, K. Hauser, S. Pyon, T. Takayama, H. Takagi, O. J. Lipscombe, S. M. Hayden, T. Kurosawa, N. Momono, M. Oda, T. Neupert, and J. Chang
Nature Communications 9, 972 (2018)  

µ+SR Investigation of the Shastry-Sutherland Compound SrCu2(BO3)2
Y. Sassa, S. Wang, J. Sugiyama, A. Amato, H.M. Ronnow, C. Ruegg, and M. Månsson
J. Phys. Soc. Japan 21, 011010 (2018)

The Metallic Quasi-1D Spin-density-Wave Compound NaV2O4 Studied by Angle-Resolved Photoelectron Spectroscopy
Y. Sassa, M. Mansson, O. K. Forslund, O. Tjernberg, V. Pomjakushin, O. Ofer, E. J. Ansaldo, J. H. Brewer, I. Umegaki, Y. Higuchi, Y. Ikedo, H. Nozaki, M. Harada, I. Watanabe, H. Sakurai, and J. Sugiyama
Journal of Electron Spectroscopy and Related Phenomena 224, 79 (2018)

Hallmarks of Hund's coupling in the Mott insulator Ca2RuO4
D. Sutter, C.G. Fatuzzo, S. Moser, M. Kim, R. Fittipaldi, A. Vecchione, V. Granata, Y. Sassa, F. Cossalter, G. Gatti, M. Grioni, H.M. Ronnow, N.C. Plumb, C.E. Matt, M. Shi, M. Hoesch, T.K. Kim, T.R. Chang, H.T. Jeng, C. Jozwiak, A. Bostwick, E. Rotenberg, A. Georges, T. Neupert, J. Chang
Nature Communications 8, 15176 (2017)

Probing two- and three-dimensional electrons in MgB2 with soft x-ray angle-resolved photoemission
Y. Sassa, M. Mansson, M. Kobayashi, O. Götberg, V. N. Strocov, T. Schmitt, N. D. Zhigadlo, O. Tjernberg, and B. Batlogg
Physical Review B 91, 045114 (2015)

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