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

Abstract

Magnetoelastic dilatometry of the piezomagnetic antiferromagnet UO2 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 UO2 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 Hc=−18 T. We present a theoretical argument that explains this unexpected behavior as a result of the reversal of the antiferromagnetic order parameter at Hc.

Signature of spin-triplet exciton condensations in LaCoO3 at ultrahigh magnetic fields up to 600 T

“…3 a–d, which is also reported in refs. 29 , 31 . We distinguish the intrinsic features and the shock propagation by carefully observing the sound speed and temperature dependence.…”

Unveiling new quantum phases in the Shastry-Sutherland compound SrCu2(BO3)2 up to the saturation magnetic field

“…In this study, we fixed the FBG using the low-temperature glue SK-229 to detect the longitudinal magnetostriction along the c axis, L c . In addition, the fiber and sample were put inside a vacuum grease to attenuate the sample vibration caused by the magneto-structural phase transitions 42 , 43 . Because of the large amount of grease coupled to the FBG, the detected magnetostriction was reduced to ~20% of the reported value 17 .…”

The Shastry-Sutherland Compound SrCu2(BO3)2 Studied up to the Saturation Magnetic Field

“…In this study, we fixed the FBG using the low-temperature glue SK-229 to detect the longitudinal magnetostriction along the c axis, L c . In addition, the fiber and sample were put deep inside a vacuum grease to attenuate the sample vibration caused by the magneto-structural phase transitions [40,41]. Because of the large amount of grease coupled to the FBG, the detected magnetostriction was reduced to ∼ 20 % of the reported value [17].…”

“…With this technique, the sample length change can be optically detected, which is a great advantage in the STC experiments. The biggest challenge performing the FBG measurement with STC is the sample vibration [40,41]. When a magneto-structural phase transition occurs, a slight lattice deformation triggers a vibration of a crystal.…”