High-pressure study of the magnetic phase transition in MnSi

Petrova, A. E.; Krasnorussky, V. N.; Lograsso, Thomas A.; Стишов, С. М.

doi:10.1103/physrevb.79.100401

Cited by 19 publications

(19 citation statements)

References 25 publications

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“…As was said in Ref. 8 :"The new measurements unambiguously show that the striking change of the magnetic susceptibility curve is a result of non-hydrostatic stresses in pressure media and has nothing to do with a change of character of the phase transition in MnSi". So the general conclusion was that the magnetic phase transition in MnSi continued to be first order in the whole pressure range studied 8 .…”

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confidence: 58%

Nature of the high-pressure tricritical point in MnSi

et al. 2009

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It is argued that M. Otero-Leal et al. [PRB 79, 060401 (2009) 1 ] wrongly identified the second order term of the Arrott equation with the coefficient at the quartic term of the Landau expansion, therefore deriving absolutely unsupported conclusions on the phase diagram of MnSi. PACS numbers: 75.30.Kz, 75.40.Cx. Despite a long history of extensive studies of the magnetic phase transition in the helimagnet MnSi its phase diagram is not completely understood. Most important but still controversial issues concerning the phase diagram of MnSi are the existence, location and nature of a tricritical point on the phase transition line in MnSi, first suggested in Ref. 2 . Since then until recently, the existence of the tricritical point has been never in doubt though its location was disputed in Ref. 3 . Meanwhile a careful study of the magnetic phase transition in MnSi confirmed a first order nature of the transition at least at ambient pressure 4,5,6 , as was proposed long ago in Ref. 7 . This observation reversed the situation. It was believed before that a second order phase transition in MnSi became first order at high pressure. Then the only conclusion could be made that the phase transition in MnSi turned to second order at high pressure. The latter of course is valid if a tricritical point does exist at the transition line. However new experiments at high pressure using helium as a pressure medium showed that the early claims on the existence of a tricritical point at the phase transition line, based on an analysis of behavior of magnetic susceptibility, are most probably a result of misinterpretation of the experimental data 8 . As was said in Ref. 8 :"The new measurements unambiguously show that the striking change of the magnetic susceptibility curve is a result of non-hydrostatic stresses in pressure media and has nothing to do with a change of character of the phase transition in MnSi". So the general conclusion was that the magnetic phase transition in MnSi continued to be first order in the whole pressure range studied 8 . In the paper 1 an attempt was made to resolve the above mentioned issues based, as the authors said, on "a direct analysis of the magnetic phase transition under pressure". Under "a direct analysis" the authors implied applications of the equationwhere H-magnetic field, M -magnetization. Equation(1), suggested by Arrott 9 , is a typical mean field relation and can be readily derived from the Landau expansion 10 . Normally the relation (1) is used to plot H/M vs M 2 (Arrott plot), which would yield a straight line at the temperature of second order ferromagnetic phase transition when the critical fluctuations can be neglected. Eq. (1) needs to be modified to account for the contribution of critical fluctuations (see Ref. 11 ). It has to be emphasized that a causal relationship between the Landau expansion and Eq.1 limited to ferromagnetic materials, since only in this case the magnetization M can serve as an order parameter with the magnetic field H as a conjugate variable. Neglectin...

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Nature of the high-pressure tricritical point in MnSi

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“…Refs. [25][26][27] for discussions of the effect of pressure hydrostaticity in other materials), low-temperature state as well as the nature of the phase transitions into it, either as a function of temperature or pressure. To address these questions a series of scattering studies as a function of pressure and temperature were made [15,16].…”

Section: Properties Of Cafe 2 As 2 As a Function Of Applied Pressurementioning

confidence: 99%

Structural, magnetic and superconducting phase transitions in CaFe2As2 under ambient and applied pressure

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Bud’ko

et al. 2009

Physica C: Superconductivity

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a b s t r a c tAt ambient pressure CaFe 2 As 2 has been found to undergo a first order phase transition from a high temperature, tetragonal phase to a low-temperature orthorhombic/antiferromagnetic phase upon cooling through T $ 170 K. With the application of pressure this phase transition is rapidly suppressed and by $0.35 GPa it is replaced by a first order phase transition to a low-temperature collapsed tetragonal, non-magnetic phase. Further application of pressure leads to an increase of the tetragonal to collapsed tetragonal phase transition temperature, with it crossing room temperature by $1.7 GPa. Given the exceptionally large and anisotropic change in unit cell dimensions associated with the collapsed tetragonal phase, the state of the pressure medium (liquid or solid) at the transition temperature has profound effects on the low-temperature state of the sample. For He-gas cells the pressure is as close to hydrostatic as possible and the transitions are sharp and the sample appears to be single phase at low temperatures. For liquid media cells at temperatures below media freezing, the CaFe 2 As 2 transforms when it is encased by a frozen media and enters into a low-temperature multi-crystallographic-phase state, leading to what appears to be a strain stabilized superconducting state at low temperatures.

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“…Moreover, this has been confirmed by neutron Larmor diffraction experiments under pressure . Conversely, data presented by Stishov et al (2007), Petrova et al (2009), and Petrova and Stishov (2012), suggests that the quantum phase transition at p = p c is either continuous or very weakly first order. Although the evidence for a pressure induced first-order transition appears convincing in the purest crystals, no agreement has been reached (OteroLeal et al, 2009a,b;Stishov, 2009).…”

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Metallic quantum ferromagnets

et al. 2016

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We give an overview of quantum phase transitions (QPTs) in metallic ferromagnets, discussing both experimental and theoretical aspects. These QPTs can be classified with respect to the presence and strength of quenched disorder: Clean systems generically show a discontinuous, or first-order, QPT from a ferromagnetic to a paramagnetic state as a function of some control parameter, as predicted by theory. Disordered systems are much more complicated, depending on the disorder strength and the distance from the QPT. In many disordered materials the QPT is continuous, or second order, and Griffiths-phase effects coexist with QPT singularities near the transition. In other systems the transition from the ferromagnetic state at low temperatures is to a different type of long-range order, such as an antiferromagnetic or a spin-density-wave state. In still other materials a transition to a state with glass-like spin dynamics is suspected. The review provides a comprehensive discussion of the current understanding of these various transitions, and of the relation between experiment and theory.

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High-pressure study of the magnetic phase transition in MnSi

Cited by 19 publications

References 25 publications

Nature of the high-pressure tricritical point in MnSi

Nature of the high-pressure tricritical point in MnSi

Structural, magnetic and superconducting phase transitions in CaFe2As2 under ambient and applied pressure

Metallic quantum ferromagnets

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