Kristina Vlášková: A2B2O7 compounds and their magnetic behavior
Venue: lecture room F2, first floor, Ke Karlovu 5 - Prague 2 | City: Prague 2
We have a pleasure to invite you to attend the joint seminar
of the Department of Condensed Matter Physics (DCMP)
and the Materials Growth and Measurement Laboratory (MGML) http://mgml.eu.
A2B2O7 compounds and their magnetic behavior
lecture given by:
Charles University, Faculty of Mathematics and Physics,
Department of Condensed Matter Physics,
Ke Karlovu 5, 121 16 Prague 2, Czech Republic
The seminar takes place in the lecture room F2
of the Faculty of Mathematics and Physics, Ke Karlovu 5, Praha 2
on Wednesday, 3.4. 2019 from 14:10
On behalf of the DCMP and MGML
Cubic A2B2O7 oxides with A standing for a rare-earth element and B for a transition or main block metal have been systematically studied for their frequently exotic crystallographic and electronic properties. Diverse ground states, magnetic structures and predicted exciting electronic, magnetic and even topological properties originating from a competition between electron-electron correlations and spin-orbit coupling have been reported [1 and references therein]. The geometrical frustration of magnetic moments residing on the A and/or B crystallographic positions offer a playground for scientific investigations as well.
A2B2O7 compounds in general crystallize either in a pyrochlore structure (F d -3 m, 227), defect-fluorite structure (F m -3 m, 225) or a low-symmetry monoclinic structure (P 1 1 21, 2 ) at ambient pressure. In both pyrochlore and defect fluorite structure A3+ and B4+ cations form a net of interpenetrating corner-sharing tetrahedra or edge sharing tetrahedra, thus they represent the canonical examples for systems with A and/or B spins are magnetically frustrated. Moreover, the diluted magnetic lattice (A/B disorder on the 4a position and A or B non-magnetic ion) is bound to have a great impact on the ground state of A2B2O7 compounds as well.
The geometrical frustration originating from the A and B atomic positions affects the magnetic behavior significantly leading in many cases to spin glass (e.g. unconventional spin glass in Y2Mo2O7 ), spin ice (e.g. geometric frustration associated with ferromagnetic interactions in Ho2Ti2O7 and Dy2Ti2O7  or ordered spin ice in Tb2Sn2O7 ) and in only a few compounds to the spin liquid states (Pr2Ir2O7 ).
We present the crystal growth and structural characterization of Er2Zr2O7 which was prepared in a single crystalline form for the first time. The low temperature properties studied by bulk measurements suggest a spin glass as a ground state. Also the results of powder neutron diffraction experiment complements the physical picture.
-  W. Witczak-Krempa et al., Annu. Rev. Condens. Matter Phys. 5 (2014) 57-82.
-  N. Ishizawa, et al., Acta Crystallographica E69 (2013) 19.
-  H.J. Silverstein et al., Phys. Rev. B 89 (2014) 054433.
-  B. Tomasello et al., Phys. Rev. B 92 (2015) 155120.
-  S. Petit et al., Phys. Rev. B 85 (2012) 054428.
-  Y. Tokiwa et al., Nature Mat. 13 (2014) 356.
- Wednesday, 03 April 2019 14:10 - 15:10