Magnetovolume effect, macroscopic hysteresis, and moment collapse in the paramagnetic state of cubic MnGe under pressure

Martín, Nicolás Bas; Deutsch, Maxime; Itié, Jean‐Paul; Rueff, Jean‐Pascal; Rößler, U.; Koepernik, Klaus; Фомичева, Л.Н.; Tsvyashchenko, A. V.; Mirebeau, I.

doi:10.1103/physrevb.93.214404

Cited by 23 publications

(21 citation statements)

References 46 publications

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“…These results indicate that not only the degree of hydrostaticity but also the compression/decompression history affects the pathways of the magnetic state transitions in CoCrFeAl HEA. The pressure hysteresis during compression and decompression implies that the PM and/or NM phases are metastable 34 . The phase transition pathways which involve metastable phases are substantially affected by the degree of hydrostaticity, the compression and decompression history, as well as rate, and sample condition (single crystal/powder, impurities) (see ref.…”

Section: Resultsmentioning

confidence: 99%

Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy

et al. 2019

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High-entropy alloys (HEAs) composed of multiple-principal elements with (nearly) equimolar ratio establish a new conceptual framework for alloy design and hold a promise for extensive applications in industry, akin to the controlled expansion alloys (CEAs), such as Invar alloys. Spontaneously, one question emerges-would it be possible to synthesize a novel class of alloys combining the virtues of both CEAs and HEAs? Here, we report the pressure-induced magnetovolume effect in the body-centered-cubic CoCrFeAl HEA coupled with magnetic phase transitions from ferromagnetic to paramagnetic, and to non-magnetic states, originating from the successive collapses of local magnetic moments of Co and Fe. The observed magnetovolume anomalies, occurring in a progressive way, tailor appreciably the coefficient of thermal expansion of CoCrFeAl. These results further strengthen HEAs' anticipated potential for designing multifunctional materials in virtue of their multiple outstanding properties, and reveal possible routes for their future synthesis.

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Section: Resultsmentioning

confidence: 99%

Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy

et al. 2019

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“…Furthermore, the slight change of antiferromagnetic moments could produce a large dis-tortion around T N because of the magneto-volume effect [46]. In itinerant magnets in which the magnetization mainly originates from the polarization of band electrons, it is known that thermal expansion tends to diverge at the magnetic transition temperature [47][48][49][50]. This effect is called a magneto-volume effect, and has been studied in various itinerant magnets [47][48][49][50].…”

Section: Discussionmentioning

confidence: 99%

“…In itinerant magnets in which the magnetization mainly originates from the polarization of band electrons, it is known that thermal expansion tends to diverge at the magnetic transition temperature [47][48][49][50]. This effect is called a magneto-volume effect, and has been studied in various itinerant magnets [47][48][49][50]. It was theoretically proposed in the framework of the self-consistent renormalization theory [51,52] that spin fluctuations near the magnetic transition temperature enhance the magneto-volume effect, as observed in MnSi [48], Gd 67 Ni 33 [49], and β-Mn…”

Section: Discussionmentioning

confidence: 99%

Enhanced magnetopiezoelectric effect at the Néel temperature in CaMn2Bi2

et al. 2019

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We have experimentally studied a magnetopiezoelectric effect (MPE), i.e. dynamic distortion caused by ac electric currents, in the antiferromagnetic conductor CaMn 2 Bi 2 at low temperatures down to 77 K using laser Doppler vibrometry. When ac electric currents are applied to CaMn 2 Bi 2 , dynamic displacement signals which increase in proportion to the current amplitude are clearly observed at 77 K, but their magnitude and temperature dependence strongly depend on Joule heating effects caused by the applied electric currents. Especially, poor thermal contact of CaMn 2 Bi 2 samples to the sample holder produces second-harmonic displacement signals owing to thermal expansion due to the Joule heating, and tends to affect the temperature dependence of the MPE signals. In a measurement run without any heating effects, a sharp enhancement of the MPE signal is observed at the Néel temperature of CaMn 2 Bi 2 , which suggests that fluctuations of itinerant Mn moments near the Néel temperature play an important role in the MPE. We speculate that electric currents produce nonequilibrium antiferromagnetic moments via the antiferromagnetic Edelstein effect and the induced antiferromagnetic momemts enhance the MPE signal with the help of a large magneto-volume coupling near the Néel temperature. The MPE efficiency as a piezoelectric response reaches 300-500 pC/N at a maximum, which is comparable to high values of piezoelectric coefficients detected in the piezoelectric (ferroelectric) ceramics.

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“…Applied pressure P, either quasihydrostatic or directional, is, in principle, a clean tuning parameter for the helimagnetic and skyrmion phase diagram of chiral magnets. To date, various high-pressure studies have been performed on the B20 compounds [25][26][27][28][29][30][31][32][33][34][35][36][37] and Cu 2 OSeO 3 [13,31,[38][39][40][41]. Here we explore the effect of quasihydrostatic pressure on the phase diagram of the latter, the archetypal insulator skyrmion host Cu 2 OSeO 3 , aiming to clarify a puzzle posed by previous highpressure work.…”

Section: Introductionmentioning

confidence: 95%

In situ control of the helical and skyrmion phases in Cu2OSeO3 using high-pressure helium gas up to 5 kbar

et al. 2020

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We report a small-angle neutron scattering study of the helical and skyrmion lattice order in singlecrystal Cu 2 OSeO 3 under quasihydrostatic helium gas pressures up to 5 kbar. By using helium gas as the pressure-transmitting medium (PTM) we ensure pressure application with improved hydrostaticity at cryogenic temperatures compared with previous reports where liquid PTMs were used. For 5-kbar He gas pressure we observe modest changes of the ambient pressure phase diagram; the critical temperature T c changes by +2.8(2)%, while in the low-T limit the helical propagation vector |q| changes by −0.5(2)%, the lower critical field H c1 changes by +2.5(1.0)%, and the upper critical field H c2 remains unchanged within uncertainty. The skyrmion phase also changes little under pressure; its largest T extent varies from T c − 2.5(5) K at ambient pressure to T c − 3.0(5) K at 5 kbar, and its location in the phase diagram follows the pressure-driven shift of T c. The weak pressure dependences of the critical magnetic fields and skyrmion phase contrast strongly with much stronger pressure-driven changes reported from previous quasihydrostatic pressure studies. Taking into account the present results and those of other uniaxial pressure data, we suggest that the results of previous quasihydrostatic pressure studies were influenced by inadvertent directional stress pressure components. Overall, our study represents a high-pressure study of the chiral magnetism in Cu 2 OSeO 3 under the most hydrostatic high-pressure conditions to date and serves also as a salient reminder of the sensitivity of chiral magnets to deviations from hydrostaticity in quasihydrostatic high-pressure studies.

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Magnetovolume effect, macroscopic hysteresis, and moment collapse in the paramagnetic state of cubic MnGe under pressure

Cited by 23 publications

References 46 publications

Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy

Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy

Enhanced magnetopiezoelectric effect at the Néel temperature in CaMn2Bi2

In situ control of the helical and skyrmion phases in Cu2OSeO3 using high-pressure helium gas up to 5 kbar

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