Coupling between magnetism and crystal structure in the antiferromagnetic UO₂

E.A. Tereshina Chitrova¹, L.V. Pourovskii^2,3, S. Khmelevskyi⁴, Z. Bao⁵, S. Daniš⁶, L. Horák⁶, T. Gouder⁵, R. Caciuffo⁵

¹Institute of Physics ASCR, Na Slovance 2, 18221 Prague, Czech Republic
²CPHT, Ecole Polytechnique, CNRS, Université Paris-Saclay, Route de Saclay, 91128 Palaiseau, France
³Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
⁴Center for Computational Materials Science, IAP, Vienna University of Technology, Vienna, Austria
⁵European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU),
Postfach 2340, DE-76125 Karlsruhe, Germany
⁶Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 12116 Prague, Czech Republic

Uranium dioxide is a major nuclear fuel and is an antiferromagnet with the Néel temperature T_N of 30.8 K [1]. The transition at T_N is accompanied by a static Jahn-Teller distortion of the oxygen cage, and strong magnetoelastic interactions that emerge from the face-centered cubic (fcc) structure. Very recent high field magnetostriction measurements showed that UO₂ is a piezomagnet and exhibits the abrupt appearance of positive linear magnetostriction, leading to a trigonal distortion [1]. In this work we observe peculiar behavior of sound velocity variation along the crystallographic axes of UO₂ at various temperatures. We employ first-principles calculations to prove a strong coupling between magnetism and crystal structure variations in UO₂. The results are compared with the thin films study where induce a tetragonal distortion in UO₂ by using different substrates [3].

1. G.H. Lander and R. Caciuffo, The fifty years it has taken to understand the dynamics of UO₂ in its ordered state, J. Phys.: Condens. Matter 32 (2020) 374001.

2. Jaime, M., Saul, A., Salamon, M. et al. Piezomagnetism and magnetoelastic memory in uranium dioxide. Nat Commun 8, 99 (2017). [3] E. A. Tereshina, Z. Bao, L. Havela, S. Daniš, C. Kuebel, T. Gouder, R. Caciuffo,

Coupling between magnetism and crystal structure in the antiferromagnetic UO2

E.A. Tereshina Chitrova1, L.V. Pourovskii2,3, S. Khmelevskyi4, Z. Bao5, S. Daniš6, L. Horák6, T. Gouder5, R. Caciuffo5

1. G.H. Lander and R. Caciuffo, The fifty years it has taken to understand the dynamics of UO2 in its ordered state, J. Phys.: Condens. Matter 32 (2020) 374001.

2. Jaime, M., Saul, A., Salamon, M. et al. Piezomagnetism and magnetoelastic memory in uranium dioxide. Nat Commun 8, 99 (2017). [3] E. A. Tereshina, Z. Bao, L. Havela, S. Daniš, C. Kuebel, T. Gouder, R. Caciuffo,

3. “Exchange bias in UO2/Fe3O4 thin films above the Néel temperature of UO2”, Appl. Phys. Lett., 105 122405 (2014).

Coupling between magnetism and crystal structure in the antiferromagnetic UO₂

E.A. Tereshina Chitrova¹, L.V. Pourovskii^2,3, S. Khmelevskyi⁴, Z. Bao⁵, S. Daniš⁶, L. Horák⁶, T. Gouder⁵, R. Caciuffo⁵

1. G.H. Lander and R. Caciuffo, The fifty years it has taken to understand the dynamics of UO₂ in its ordered state, J. Phys.: Condens. Matter 32 (2020) 374001.

3. “Exchange bias in UO₂/Fe₃O₄ thin films above the Néel temperature of UO₂”, Appl. Phys. Lett., 105 122405 (2014).