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@INPROCEEDINGS{Maraytta:890691,
      author       = {Maraytta, Nour},
      title        = {{S}tructure and {D}ynamics of {M}agnetocaloric {M}aterials},
      reportid     = {FZJ-2021-01133},
      year         = {2021},
      abstract     = {The search for more efficient use of energy has been
                      leading to a growing interest in the research field of
                      magnetocaloric materials. The magnetocaloric effect (MCE)
                      describes the change of temperature or entropy of a material
                      when exposed to a change of the magnetic field and forms the
                      basis of magnetocaloric refrigeration technologies [1].In
                      the last years there has been an upsurge in the knowledge of
                      the MCE and many materials have been investigated for their
                      MCE characteristics [2]. In the context of this talk, I will
                      present the field direction dependence of the
                      thermo-magnetic behavior in single crystalline compounds
                      MnFe4Si3 and Mn5Ge3. The emphasis will be on the direct
                      measurement of the adiabatic temperature change ΔTad in
                      pulsed magnetic fields as it provides the opportunity to
                      examine the sample temperature response to the magnetic
                      field on a time scale close to the real process used in
                      applications [3]. A discussion of how the anisotropy affects
                      the magnetocaloric effect and a comparison between MnFe4Si3
                      compound, which exhibits easy plane anisotropy, and Mn5Ge3
                      which features uniaxial anisotropy, will be also presented
                      [4].The Mn5Si3 compound exhibits inverse MCE related to the
                      antiferromagnetic order phase transition AF1 to AF2, and
                      direct MCE related to the AF2 to the paramagnetic phase
                      transitions. Previous studies indicate a transition from the
                      AF1 to AF1' before reaching the AF2 phase [5]. The magnetic
                      structures of the AF1 and AF2 phases have been established
                      [6, 7], while the magnetic structure of the AF1' phase has
                      not been studied before. Therefore, the second part of the
                      talk will be devoted to discuss the results of the
                      investigation of the nuclear and magnetic structure of the
                      intermediate phase AF1' of the single crystalline compound
                      Mn5Si3.[1] K. A. Gschneidner Jr. and V.K. Pecharsky,
                      “Thirty years of near room temperature magnetic cooling:
                      Where we are today and future prospects”, International
                      Journal of Refrigeration, 31, 945(2008).[2] V. Franco, J. S.
                      Blazquez, B. Ingale, and A. Conde, “The magnetocaloric
                      effect and magnetic refrigeration near room temperature:
                      Materials and models”, Annual Review of Materials
                      Research, 42, 305(2012).[3] N. Maraytta, Y. Skourski, J.
                      Voigt, K. Friese, M. G. Herrmann, J. Perßon, J. Wosnitza,
                      S. M. Salman, and T. Brückel, “Direct measurements of the
                      magneto-caloric effect of MnFe4Si3 in pulsed magnetic
                      fields”, Journal of Alloys and Compounds, 805,
                      1161(2019).[4] N. Maraytta, J. Voigt, C. S. Mejia, K.
                      Friese, Y. Skourski, J. Perßon, S. M. Salman, and T.
                      Brückel, “Anisotropy of the magnetocaloric effect:
                      Example of Mn5Ge3”, Journal of Applied Physics, 128,
                      103903(2020).[5] M. R. Silva, P. J. Brown, and J. B.
                      Forsyth, “Magnetic moments and magnetic site
                      susceptibilities in Mn5Si3”, Journal of Physics: Condensed
                      Matter, 14, 8707(2002).[6] P. J. Brown, J. B. Forsyth, V.
                      Nunez, and F. Tasset, “The low-temperature
                      antiferromagnetic structure of Mn5Si3 revised in the light
                      of neutron polarimetry”, Journal of Physics: Condensed
                      Matter, 4, 10025 (1992).[7] P. J. Brown and J. B. Forsyth,
                      “Antiferromagnetism in Mn5Si3: The magnetic structure of
                      the AF2 phase at 70 K”, Journal of Physics: Condensed
                      Matter, 7, 7619(1995).},
      month         = {Feb},
      date          = {2021-02-25},
      organization  = {Digital Institute Seminar JCNS-2,
                       Forschungszentrum Jülich GmbH
                       (Germany), 25 Feb 2021 - 25 Feb 2021},
      subtyp        = {Invited},
      cin          = {JCNS-2 / PGI-4 / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-4-20110106 /
                      $I:(DE-82)080009_20140620$},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (FZJ) (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)31},
      url          = {https://juser.fz-juelich.de/record/890691},
}