Magnetoelastic standing waves induced in UO 2 by microsecond magnetic field pulses

Rico Schönemann (1) , George Rodriguez (2) , Dwight Rickel (1) , Fedor Balakirev (1) , Ross D Mcdonald (1) , Jordan Evans (1, 3) , Boris Maiorov (1) , Charles Paillard (4) , Laurent Bellaiche (5) , Andreas Stier (1) , Myron B Salamon (1) , Krzysztof Gofryk (3) , Marcelo Jaime (1)

1 Materials Physics and Applications Division
2 Detonation Science and Technology, Los Alamos National Laboratory, Los Alamos, NM 87545;
3 Nuclear Fuels and Materials Division, Idaho National Laboratory, Idaho Falls, ID 83415;
4 SPMS - Laboratoire Structures, Propriétés et Modélisation des solides
5 Institute for nanosciences and engineering and physics departement [University of Arkansas]

Magnetoelastic dilatometry of the piezomagnetic antiferromagnet UO 2 was performed via the fiber Bragg grating method in magnetic fields up to 150 T generated by a single-turn coil setup. We show that in microsecond timescales, pulsed-magnetic fields excite mechanical resonances at temperatures ranging from 10 to 300 K, in the paramagnetic as well as within the robust antiferromagnetic state of the material. These resonances, which are barely attenuated within the 100-µs observation window, are attributed to the strong magnetoelastic coupling in UO 2 combined with the high crystalline quality of the single crystal samples. They compare well with mechanical resonances obtained by a resonant ultrasound technique and superimpose on the known nonmonotonic magnetostriction background. A clear phase shift of π in the lattice oscillations is observed in the antiferromagnetic state when the magnetic field overcomes the piezomagnetic switch field H c = − 18 T. We present a theoretical argument that explains this unexpected behavior as a result of the reversal of the antiferromagnetic order parameter at H c.

Domaines: Physique [physics]

Rico Schönemann, George Rodriguez, Dwight Rickel, Fedor Balakirev, Ross D Mcdonald, et al.. Magnetoelastic standing waves induced in UO 2 by microsecond magnetic field pulses. Proceedings of the National Academy of Sciences of the United States of America, 2021, 118 (51), pp.e2110555118. ⟨10.1073/pnas.2110555118⟩. ⟨hal-03582715⟩