We investigate the structure and the magnetic properties of magnetic compounds using scanning tunnelling microscopy (STM/AFM) experiments and x-ray absorption spectroscopy, as well as first-principle calculations.
Ref:
Journal of Magnetism and Magnetic Materials, Volume 352, p. 49-55.
DOI: 10.1016/j.jmmm.2013.10.011
2. J. Appl. Phys. 118, 133903 (2015);
Abnormal thermal expansion, multiple transitions, magnetocaloric effect, and electronic structure of Gd6Co4.85 http://scitation.aip.org/content/aip/journal/jap/118/13/10.1063/1.4931982
http://dx.doi.org/10.1063/1.4931982
3. Zeitschrift für anorganische und allgemeine Chemie, Special Issue: Dedicated to Professor Reinhard Nesper on the Occasion of His 65th Birthday
Volume 640, Issue 5, pages 738–752, April 2014. DOI: 10.1002/zaac.201300665
Guido Kreiner, Adel Kalache, Steffen Hausdorf, Vajiheh Alijani, Jin-Feng Qian, Guangcun Shan, Ulrich Burkhardt, Siham Ouardi, Claudia Felser*
Z. anorg. allg. Chem. 2014, vol. 640, p. 738
We investigate the geometric structure and the magnetic properties of surfaces and ultra thin films using scanning tunnelling microscopy, magneto-optic Kerr effect experiments and x-ray absorption spectroscopy. The long-sought quantum anomalous Hall effect was realized in the magnetic topological insulator. However, the requirement of an extremely low temperature (approximately 30~mK) hinders realistic applications. Based on ab-initio band structure calculations, we propose a quantum anomalous Hall platform with a large energy gap of 0.34 and 0.06 ~eV on honeycomb lattices comprised of Sn and Ge, respectively. The ferromagnetic (FM) order forms in one sublattice of the honeycomb structure by controlling the surface functionalization rather than dilute magnetic doping, {\color{black}which is expected to be visualized by spin polarized STM in experiment}. Strong coupling between the inherent quantum spin Hall state and ferromagnetism results in considerable exchange splitting and consequently an FM insulator with a large energy gap. The estimated mean-field Curie temperature is 243 and 509~K for Sn and Ge lattices, respectively. The large energy gap and high Curie temperature indicate the feasibility of the quantum anomalous Hall effect in the near-room-temperature and even room-temperature regions.
https://journals.aps.org/prl/accepted/fa072Yd7Fcd1a64a95f85df1acd1ea4d540cb10e1
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.256401
Magnons are the elementary magnetic excitations in a magnetically ordered solid. The physical properties of magnons strongly depend on their wavevector (wavelength). If the wavelength is comparable to the lattice constant, the magnons are governed by the microscopic exchange interaction and hence the experimental results on such magnon modes provide a true microscopic picture of the system.