Helical magnetic order in MnSi thin films

Karhu, Eric; Kahwaji, Samer; Robertson, M.; Fritzsche, H.; Kirby, Brian J.; Majkrzak, C. F.; Monchesky, T. L.

doi:10.1103/physrevb.84.060404

Cited by 62 publications

(99 citation statements)

References 18 publications

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“…Phase transitions in thin films with non-collinear ground states have been only recently studied [15][16][17][18]25]. MC simulations of a helimagnetic thin film [26] and a few experiments in helimagnets [27,28] have also been carried out. These investigations were motivated by the fact that helical magnets present a great potential of applications in spintronics with spindependent electron transport [29][30][31].…”

Section: Phase Transitionmentioning

confidence: 99%

Partial phase transition and quantum effects in helimagnetic films under an applied magnetic field

Hog

Diep

2017

Journal of Magnetism and Magnetic Materials

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We study the phase transition in a helimagnetic film with Heisenberg spins under an applied magnetic field in the c direction perpendicular to the film. The helical structure is due to the antiferromagnetic interaction between next-nearest neighbors in the c direction. Helimagnetic films in zero field are known to have a strong modification of the in-plane helical angle near the film surfaces. We show that spins react to a moderate applied magnetic field by creating a particular spin configuration along the c axis. With increasing temperature (T ), using Monte Carlo simulations we show that the system undergoes a phase transition triggered by the destruction of the ordering of a number of layers. This partial phase transition is shown to be intimately related to the ground-state spin structure. We show why some layers undergo a phase transition while others do not. The Green's function method for non collinear magnets is also carried out to investigate effects of quantum fluctuations. Non-uniform zero-point spin contractions and a crossover of layer magnetizations at low T are shown and discussed.

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Section: Phase Transitionmentioning

confidence: 99%

Partial phase transition and quantum effects in helimagnetic films under an applied magnetic field

Hog

Diep

2017

Journal of Magnetism and Magnetic Materials

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“…[30][31][32][33] We have shown that the helical magnetic order is preserved in MnSi(111) films grown on Si(111), which makes this material attractive for spintronics studies of helical magnets. We calculate the magnetic phase diagram for the phenomenological Dzyaloshinskii model 1 with easy-plane uniaxial anisotropy in applied magnetic fields transverse to the axis in order to predict the stable modulations of the magnetic order that can be observed in the chiral magnetic thin films.…”

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confidence: 99%

Chiral modulations and reorientation effects in MnSi thin films

et al. 2012

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We present an experimental and theoretical investigation of the influence of a uniaxial magnetocrystalline anisotropy on the magnetic textures that are formed in a chiral magnetic system. We show that the epitaxially induced tensile stress in MnSi thin films grown on Si (111) creates an easy-plane uniaxial anisotropy. The magnetoelastic shear stress coefficient is derived from SQUID magnetometry measurements in combination with transmission electron microscopy and x-ray diffraction data. Density functional calculations of the magnetoelastic coefficient support the conclusion that the uniaxial anisotropy originates from the magnetoelastic coupling. Theoretical calculations based on a Dzyaloshinskii model that includes an easy-plane anisotropy predict a variety of modulations to the magnetic order that are not observed in bulk MnSi crystals. Evidence for these states is found in the magnetic hysteresis and polarized neutron reflectometry measurements.

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“…The drop in the form factor at Q = 0 implies that the low-Q upturn is not due to skyrmions and must be due to longer length scale features. The chiral grain boundaries set a second length scale for the problem that is of the order of several hundred nanometers 31 . Although the differential SANS measurement removes the nuclear contribution from the signal, the grain boundaries imprint their structure on the magnetic texture.…”

Section: B Sansmentioning

confidence: 99%

“…Anisotropy is of importance for understanding the magnetic structure of chiral magnetic epilayers grown on Si(111) substrates, including MnSi [30][31][32] , FeGe 33 , Fe x Co 1−x Si 34,35 and MnGe 36 .…”

Section: Introductionmentioning

confidence: 99%

Neutron study of in-plane skyrmions in MnSi thin films

et al. 2017

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The magnetic structure of the in-plane skyrmions in epitaxial MnSi/Si(111) thin films is probed in three dimensions by the combination of polarized neutron reflectometry (PNR) and small angle neutron scattering (SANS). We demonstrate that skyrmions exist in a region of the phase diagram above at temperature of 10 K. PNR shows the skyrmions are confined to the middle of the film due to the potential well formed by the surface twists. However, SANS shows that there is considerable disorder within the plane indicating that the magnetic structure is a 2D skyrmion glass.

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Helical magnetic order in MnSi thin films

Abstract: Helical magnetic order in MnSi thin films

Cited by 62 publications

References 18 publications

Partial phase transition and quantum effects in helimagnetic films under an applied magnetic field

Partial phase transition and quantum effects in helimagnetic films under an applied magnetic field

Chiral modulations and reorientation effects in MnSi thin films

Neutron study of in-plane skyrmions in MnSi thin films

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