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O Chubykalofesenko - One of the best experts on this subject based on the ideXlab platform.

  • controlling the polarity of the transient ferromagneticlike state in ferrimagnets
    Physical Review B, 2014
    Co-Authors: U Atxitia, Joseph Barker, R W Chantrell, O Chubykalofesenko
    Abstract:

    It was recently observed that the two antiferromagnetically coupled sublattices of a rare earth-transition metal ferrimagnet can temporarily align ferromagnetically during femtosecond laser heating, but always with the transition metal aligning in the rare earth direction. This behavior has been attributed to the slower magnetization dynamics of the rare earth sublattice. The aim of this work was to assess how the difference in the speed of the transition metal and rare earth dynamics affects the formation of the transient ferromagneticlike state and consequently controls its formation. Our investigation was performed using extensive atomistic spin simulations and analytic micromagnetic theory of ferrimagnets, with analysis of a large area of parameter space such as initial temperature, Gd concentration, and laser fluence. Surprisingly, we found that at high temperatures, close to the Curie point, the rare earth dynamics become faster than those of the transition metal. Subsequently we show that the transient state can be formed with the opposite polarity, where the rare earth aligns in the transition metal direction. Our findings shed light on the complex behavior of this class of Ferrimagnetic Materials and highlight an important feature which must be considered, or even exploited, if these Materials are to be used in ultrafast magnetic devices.

  • landau lifshitz bloch equation for Ferrimagnetic Materials
    Physical Review B, 2012
    Co-Authors: U Atxitia, P Nieves, O Chubykalofesenko
    Abstract:

    We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component magnetic system valid up to the Curie temperature. As an example, we consider disordered GdFeCo ferrimagnet where the ultrafast optically induced magnetization switching under the action of heat alone has been recently reported. The two-component LLB equation contains the longitudinal relaxation terms responding to the exchange fields from the proper and the neighboring sublattices. We show that the sign of the longitudinal relaxation rate at high temperatures can change depending on the dynamical magnetization value and a dynamical polarisation of one material by another can occur. We discuss the differences between the LLB and the Baryakhtar equation, recently used to explain the ultrafast switching in ferrimagnets. The two-component LLB equation forms basis for the largescale micromagnetic modeling of nanostructures at high temperatures and ultrashort timescales.

  • landau lifshitz bloch equation for Ferrimagnetic Materials
    Physical Review B, 2012
    Co-Authors: U Atxitia, P Nieves, O Chubykalofesenko
    Abstract:

    We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component magnetic system valid up to the Curie temperature. As an example, we consider disordered GdFeCo ferrimagnet where the ultrafast optically induced magnetization switching under the action of heat alone has been recently reported. The two-component LLB equation contains the longitudinal relaxation terms responding to the exchange fields from the proper and the neighboring sublattices. We show that the sign of the longitudinal relaxation rate at high temperatures can change depending on the dynamical magnetization value and a dynamical polarization of one material by another can occur. We discuss the differences between the LLB and the Baryakhtar equations, recently used to explain the ultrafast switching in ferrimagnets. The two-component LLB equation forms the basis for the large-scale micromagnetic modeling of nanostructures at high temperatures and ultrashort time scales.

U Atxitia - One of the best experts on this subject based on the ideXlab platform.

  • controlling the polarity of the transient ferromagneticlike state in ferrimagnets
    Physical Review B, 2014
    Co-Authors: U Atxitia, Joseph Barker, R W Chantrell, O Chubykalofesenko
    Abstract:

    It was recently observed that the two antiferromagnetically coupled sublattices of a rare earth-transition metal ferrimagnet can temporarily align ferromagnetically during femtosecond laser heating, but always with the transition metal aligning in the rare earth direction. This behavior has been attributed to the slower magnetization dynamics of the rare earth sublattice. The aim of this work was to assess how the difference in the speed of the transition metal and rare earth dynamics affects the formation of the transient ferromagneticlike state and consequently controls its formation. Our investigation was performed using extensive atomistic spin simulations and analytic micromagnetic theory of ferrimagnets, with analysis of a large area of parameter space such as initial temperature, Gd concentration, and laser fluence. Surprisingly, we found that at high temperatures, close to the Curie point, the rare earth dynamics become faster than those of the transition metal. Subsequently we show that the transient state can be formed with the opposite polarity, where the rare earth aligns in the transition metal direction. Our findings shed light on the complex behavior of this class of Ferrimagnetic Materials and highlight an important feature which must be considered, or even exploited, if these Materials are to be used in ultrafast magnetic devices.

  • landau lifshitz bloch equation for Ferrimagnetic Materials
    Physical Review B, 2012
    Co-Authors: U Atxitia, P Nieves, O Chubykalofesenko
    Abstract:

    We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component magnetic system valid up to the Curie temperature. As an example, we consider disordered GdFeCo ferrimagnet where the ultrafast optically induced magnetization switching under the action of heat alone has been recently reported. The two-component LLB equation contains the longitudinal relaxation terms responding to the exchange fields from the proper and the neighboring sublattices. We show that the sign of the longitudinal relaxation rate at high temperatures can change depending on the dynamical magnetization value and a dynamical polarisation of one material by another can occur. We discuss the differences between the LLB and the Baryakhtar equation, recently used to explain the ultrafast switching in ferrimagnets. The two-component LLB equation forms basis for the largescale micromagnetic modeling of nanostructures at high temperatures and ultrashort timescales.

  • landau lifshitz bloch equation for Ferrimagnetic Materials
    Physical Review B, 2012
    Co-Authors: U Atxitia, P Nieves, O Chubykalofesenko
    Abstract:

    We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component magnetic system valid up to the Curie temperature. As an example, we consider disordered GdFeCo ferrimagnet where the ultrafast optically induced magnetization switching under the action of heat alone has been recently reported. The two-component LLB equation contains the longitudinal relaxation terms responding to the exchange fields from the proper and the neighboring sublattices. We show that the sign of the longitudinal relaxation rate at high temperatures can change depending on the dynamical magnetization value and a dynamical polarization of one material by another can occur. We discuss the differences between the LLB and the Baryakhtar equations, recently used to explain the ultrafast switching in ferrimagnets. The two-component LLB equation forms the basis for the large-scale micromagnetic modeling of nanostructures at high temperatures and ultrashort time scales.

Vitaliy Lomakin - One of the best experts on this subject based on the ideXlab platform.

  • landau lifshitz bloch equation for ferrimagnets with higher order interaction
    Physical Review B, 2021
    Co-Authors: Marco Menarini, Vitaliy Lomakin
    Abstract:

    This paper presents a micromagnetic formulation for modeling the magnetization dynamics and thermal equilibrium in Ferrimagnetic Materials at low and elevated temperatures. The formulation is based on a mean field approximation (MFA). In this formulation, the ferrimagnet is described micromagnetically by two coupled sublattices, including inter- and intra-lattice micromagnetic exchange as well as four-spin interactions via an inter-lattice molecular field and a perpendicular field with a cubic dependence of the magnetization. The MFA is used to derive a Landau Lifshitz Bloch equation for Ferrimagnetic material, including cases with a ferromagnetic - antiferromagnetic phase transitions. This micromagnetic formulation is used for modeling the phase transitions in FeRh and it shown an agreement with results presented in recent experiments and atomistic models.

Dylan Rees - One of the best experts on this subject based on the ideXlab platform.

  • large magneto optical kerr effect and imaging of magnetic octupole domains in an antiferromagnetic metal
    arXiv: Materials Science, 2018
    Co-Authors: Tomoya Higo, Huiyuan Man, Daniel B Gopman, Takashi Koretsune, Olaf M J Van T Erve, Yury P Kabanov, Dylan Rees
    Abstract:

    When a polarized light beam is incident upon the surface of a magnetic material, the reflected light undergoes a polarization rotation. This magneto-optical Kerr effect (MOKE) has been intensively studied in a variety of ferro- and Ferrimagnetic Materials because it provides a powerful probe for electronic and magnetic properties as well as for various applications including magneto-optical recording. Recently, there has been a surge of interest in antiferromagnets (AFMs) as prospective spintronic Materials for high-density and ultrafast memory devices, owing to their vanishingly small stray field and orders of magnitude faster spin dynamics compared to their ferromagnetic counterparts. In fact, the MOKE has proven useful for the study and application of the antiferromagnetic (AF) state. Although limited to insulators, certain types of AFMs are known to exhibit a large MOKE, as they are weak ferromagnets due to canting of the otherwise collinear spin structure. Here we report the first observation of a large MOKE signal in an AF metal at room temperature. In particular, we find that despite a vanishingly small magnetization of $M \sim$0.002 $\mu_{\rm B}$/Mn, the non-collinear AF metal Mn$_3$Sn exhibits a large zero-field MOKE with a polar Kerr rotation angle of 20 milli-degrees, comparable to ferromagnetic metals. Our first-principles calculations have clarified that ferroic ordering of magnetic octupoles in the non-collinear Neel state may cause a large MOKE even in its fully compensated AF state without spin magnetization. This large MOKE further allows imaging of the magnetic octupole domains and their reversal induced by magnetic field. The observation of a large MOKE in an AF metal should open new avenues for the study of domain dynamics as well as spintronics using AFMs.

  • large magneto optical kerr effect and imaging of magnetic octupole domains in an antiferromagnetic metal
    Nature Photonics, 2018
    Co-Authors: Tomoya Higo, Huiyuan Man, Daniel B Gopman, Takashi Koretsune, Olaf M J Van T Erve, Yury P Kabanov, Dylan Rees
    Abstract:

    The magneto-optical Kerr effect (MOKE) has been intensively studied in a variety of ferro- and Ferrimagnetic Materials as a powerful probe for electronic and magnetic properties1–3 and for magneto-optical technologies 4 . The MOKE can be additionally useful for the investigation of the antiferromagnetic (AF) state, although thus far limited to insulators5–9. Here, we report the first observation of the MOKE in an AF metal. In particular, we find that the non-collinear AF metal Mn3Sn (ref. 10 ) exhibits a large zero-field Kerr rotation angle of 20 mdeg at room temperature, comparable to ferromagnetic metals. Our first-principles calculations clarify that ferroic ordering of magnetic octupoles 11 produces a large MOKE even in its fully compensated AF state. This large MOKE further allows imaging of the magnetic octupole domains and their reversal. The observation of a large MOKE in an AF metal will open new avenues for the study of domain dynamics as well as spintronics using antiferromagnets12–16.

P Nieves - One of the best experts on this subject based on the ideXlab platform.

  • landau lifshitz bloch equation for Ferrimagnetic Materials
    Physical Review B, 2012
    Co-Authors: U Atxitia, P Nieves, O Chubykalofesenko
    Abstract:

    We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component magnetic system valid up to the Curie temperature. As an example, we consider disordered GdFeCo ferrimagnet where the ultrafast optically induced magnetization switching under the action of heat alone has been recently reported. The two-component LLB equation contains the longitudinal relaxation terms responding to the exchange fields from the proper and the neighboring sublattices. We show that the sign of the longitudinal relaxation rate at high temperatures can change depending on the dynamical magnetization value and a dynamical polarisation of one material by another can occur. We discuss the differences between the LLB and the Baryakhtar equation, recently used to explain the ultrafast switching in ferrimagnets. The two-component LLB equation forms basis for the largescale micromagnetic modeling of nanostructures at high temperatures and ultrashort timescales.

  • landau lifshitz bloch equation for Ferrimagnetic Materials
    Physical Review B, 2012
    Co-Authors: U Atxitia, P Nieves, O Chubykalofesenko
    Abstract:

    We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component magnetic system valid up to the Curie temperature. As an example, we consider disordered GdFeCo ferrimagnet where the ultrafast optically induced magnetization switching under the action of heat alone has been recently reported. The two-component LLB equation contains the longitudinal relaxation terms responding to the exchange fields from the proper and the neighboring sublattices. We show that the sign of the longitudinal relaxation rate at high temperatures can change depending on the dynamical magnetization value and a dynamical polarization of one material by another can occur. We discuss the differences between the LLB and the Baryakhtar equations, recently used to explain the ultrafast switching in ferrimagnets. The two-component LLB equation forms the basis for the large-scale micromagnetic modeling of nanostructures at high temperatures and ultrashort time scales.