Magnetic fluctuations and correlations in MnSi: Evidence for a chiral skyrmion spin liquid phase

Pappas, C.; Lelièvre‐Berna, E.; Bentley, P.; Falus, Péter; Fouquet, Peter; Faragó, B.

doi:10.1103/physrevb.83.224405

Cited by 45 publications

(56 citation statements)

References 34 publications

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“…In combination with experimental results on MnSi [37,41], Mn 1−y Co y Si [9], and Mn 1−z Fe z Si [42] obtained by different neutron scattering techniques this provides profound evidence for complex magnetic states in the precursor region of cubic helimagnets. Theoretically these phenomena can be understood by the nucleation of modulated magnetic states composed of confined chiral solitons as described in section 2.…”

Section: Discussionmentioning

confidence: 92%

“…The sense of the magnetization rotation is fixed due to the presence of the chiral DzyaloshinskiiMoriya (DM) interaction [20,21]. However, in their magnetic field−temperature, (H, T ), phase diagrams, as sketched in figure 1(a), numerous puzzling physical anomalies have been observed in a narrow temperature interval in the vicinity of T C [8,10,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42]. The origin of these "precursor anomalies" (hatched area in figure 1(a)) and notably the magnetic structure of the so-called A phase is a long-standing and intriguing problem in chiral magnetism.…”

Section: Introductionmentioning

confidence: 99%

“…The prediction of a possible formation of such magnetic vortices in non-centrosymmetric ferromagnets in general [43,44] and in cubic helimagnets in particular [45,46,47] have triggered an intensive quest for these exotic states [7,10,32,33,34,37,38,39,40,41,42,48,49]. Of particular interest in the experimental investigations is the A phase, a small area below T C reported for MnSi many years ago [24,25].…”

Section: Introductionmentioning

confidence: 99%

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Confinement of chiral magnetic modulations in the precursor region of FeGe

Wilhelm

Baenitz

Schmidt

et al. 2012

J. Phys.: Condens. Matter

111

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Abstract. We report on magnetic susceptibility and specific heat measurements of the cubic helimagnet FeGe in external magnetic fields and temperatures near the onset of long-range magnetic order at T C = 278.2(3) K. Pronounced anomalies in the field-dependent χac(H) data as well as in the corresponding imaginary part χ ac (H) reveal a precursor region around T C in the magnetic phase diagram. The occurrence of a maximum at T 0 = 279.6 K in the zero-field specific heat data indicates a second order transition into a magnetically ordered state. A shoulder evolves above this maximum as a magnetic field is applied. The field dependence of both features coincides with crossover lines from the field-polarized to the paramagnetic state deduced from χac(T ) at constant magnetic fields. The experimental findings are analyzed within the standard Dzyaloshinskii theory for cubic helimagnets. The remarkable multiplicity of modulated precursor states and the complexity of the magnetic phase diagram near the magnetic ordering are explained by the change of the character of solitonic inter-core interactions and the onset of specific confined chiral modulations in this area.

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Confinement of chiral magnetic modulations in the precursor region of FeGe

Wilhelm

Baenitz

Schmidt

et al. 2012

J. Phys.: Condens. Matter

111

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“…As is recognized now the sharp peaks in the above properties indicate a first order nature of the phase transition whereas the origin of the shoulders is still not quite clear [4][5][6][7][8] . There is some evidence that the shoulders arise from intense helical (chiral) fluctuations in the vicinity of the phase transition in MnSi [8][9][10] . These fluctuations must be responsible for the first order phase transition in MnSi, symmetry of which principally allows a second order one 11,12 .…”

Section: Introductionmentioning

confidence: 99%

Comparative study of helimagnets MnSi andCu2OSeO3at high pressures

et al. 2014

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The heat capacity of helical magnets Cu2OSeO3 and MnSi has been investigated at high pressures by the ac-calorimetric technique. Despite the differing nature of their magnetic moments, Cu2OSeO3 and MnSi demonstrate a surprising similarity in behavior of their magnetic and thermodynamic properties at the phase transition. Two characteristic features of the heat capacity at the phase transitions of both substances (peak and shoulder) behave also in a similar way at high pressures if analyzed as a function of temperature. This probably implies that the longitudinal spin fluctuations typical of weak itinerant magnets like MnSi contribute little to the phase transition. The shoulders of the heat capacity curves shrink with decreasing temperature suggesting that they arise from classical fluctuations. In case of MnSi the sharp peak and shoulder at the heat capacity disappear simultaneously probably signifying the existence of a tricritical point and confirming the fluctuation nature of the first order phase transition in MnSi as well as in Cu2OSeO3.

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“…The helical transition at zero magnetic field is of first order [8][9][10][11][12] and preceded by strong chiral fluctuating correlations. These build up just above T C leading to intense diffuse scattering of neutrons that spreads homogeneously on the surface of a sphere with radius τ ¼ 2π=l, with l being the pitch of the helix [13].…”

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confidence: 99%

Magnetic Fluctuations, Precursor Phenomena, and Phase Transition in MnSi under a Magnetic Field

et al. 2017

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The reference chiral helimagnet MnSi is the first system where skyrmion lattice correlations have been reported. At zero magnetic field the transition at TC to the helimagnetic state is of first order. Above TC , in a region dominated by precursor phenomena, neutron scattering shows the build up of strong chiral fluctuating correlations over the surface of a sphere with radius 2π/ , where is the pitch of the helix. It has been suggested that these fluctuating correlations drive the helical transition to first order following a scenario proposed by Brazovskii for liquid crystals. We present a comprehensive neutron scattering study under magnetic fields, which provides evidence that this is not the case. The sharp first order transition persists for magnetic fields up to 0.4 T whereas the fluctuating correlations weaken and start to concentrate along the field direction already above 0.2 T. Our results thus disconnect the first order nature of the transition from the precursor fluctuating correlations. They also show no indication for a tricritical point, where the first order transition crosses over to second order with increasing magnetic field. In this light, the nature of the first order helical transition and the precursor phenomena above TC , both of general relevance to chiral magnetism, remain an open question.

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Magnetic fluctuations and correlations in MnSi: Evidence for a chiral skyrmion spin liquid phase

Cited by 45 publications

References 34 publications

Confinement of chiral magnetic modulations in the precursor region of FeGe

Confinement of chiral magnetic modulations in the precursor region of FeGe

Comparative study of helimagnets MnSi andCu2OSeO3at high pressures

Magnetic Fluctuations, Precursor Phenomena, and Phase Transition in MnSi under a Magnetic Field

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