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@INPROCEEDINGS{Shen:1034060,
      author       = {Shen, Enlin and Schmalzl, Karin and Qureshi, Navid and
                      Stock, Chris},
      title        = {{A}coustic {I}nstabilities of {C}u{F}e2{O}4},
      reportid     = {FZJ-2024-06881},
      year         = {2024},
      abstract     = {MotivationThe tetragonal distortion in spinel structures,
                      such as CuFe2O4, CuCr2O4, and NiCr2O4, has
                      garneredsignificant attention due to its profound influence
                      on structural and magnetic properties [1].Among these,
                      CuFe2O4 is unique as it is ferromagnetic at room
                      temperature. The tetragonal distortionin CuFe2O4 has been
                      explained using semicovalent bonding [2] and the Jahn-Teller
                      effect [3].The transition from a tetragonal to a cubic
                      structure upon heating has been the subject of
                      ongoingresearch. Bertaut [4] initially proposed a transition
                      temperature of 760℃, but subsequent studiesby Miyahara and
                      Ohnishi [5] using high-temperature X-ray diffraction and
                      heat analysis correctedthis value to approximately 400℃.
                      This transition occurs below the magnetic Curie
                      temperature,highlighting the coupling between structural and
                      magnetic properties. Additionally, Takei et al. [6]and
                      Forrer et al. [7] observed anomalies near 390℃, consistent
                      with this structural phase transition.These findings
                      motivate further studies on CuFe2O4 to understand its
                      temperature-dependentstructural transitions, magnetoelastic
                      coupling, and associated changes in elastic constants. Such
                      investigationsprovide key insights into the material’s
                      fundamental physics and potential applicationsin
                      magnetostrictive and multiferroic devices.Findings and
                      future planCuFe2O4 demonstrates complex structural and
                      acoustic transitions driven by temperature variations.The
                      tetrahedral structure transitions to a cubic phase with
                      increasing temperature as evidenced byX-ray diffraction.
                      Elastic neutron scattering reveals temperature-induced
                      changes in the Lorentzianscale and width. The scale
                      decreases with increasing temperature, while the width
                      broadens, indicatingevolving elastic properties. These
                      trends align with fitting models, confirming the
                      consistencyof our interpretation.Inelastic neutron
                      scattering along Q = [1,￣1, 0] at room temperature reveals
                      the relationship betweenthe Lorentzian peak position and the
                      acoustic rate. The acoustic rate, defined by the Lorentzian
                      peakposition, is directly linked to the elastic constant
                      c11-c12. Shifts in the Lorentzian peak position andwidth
                      with increasing temperature provide insights into the
                      softening of elastic constants, with ourfittings confirming
                      these trends.Future experiments will refine the
                      understanding of these transitions, expanding measurements
                      ofelastic constants and exploring scattering along
                      additional directions. These efforts aim to advanceknowledge
                      of the interplay between structural, acoustic, and magnetic
                      properties in CuFe2O4.[1] T. Inoue and S. Iida. Specific
                      heats of copper ferrite. J. Phys. Soc. Japan, 13, 1958.[2]
                      J. B. Goodenough and A. L. Loeb. Specific heats of copper
                      ferrite. Phys. Rev., 98:391,1955.[3] J. D. Dunitz and L. E.
                      Orgel. Jahn-teller effect and the structure of copper
                      ferrite.J. Phys. Chem. Solid., 3:20, 1957.[4] E. F. Bertaut.
                      Structural transitions in cufe2o4. Compt. Rend., 230:213,
                      1950.[5] S. Miyahara and H. Ohnishi. The phase transition in
                      cufe2o4 as observed by x-raydiffraction at high temperature.
                      J. Phys. Soc. Japan, 12:1296, 1956.[6] T. Yasuda T. Takei
                      and S. Ishihara. Anomalous behavior of magnetization in
                      cufe2o4.Denkigakkai Shi in Japan, 59:568, 1939.[7] R. Baffle
                      R. Forrer and P. Fourinier. Magnetic properties of copper
                      ferrites. J. de Phys., 6:71,1945.},
      month         = {Dec},
      date          = {2024-12-11},
      organization  = {Flipper 2024 as a satellite workshop
                       of the ILL/ESS user meeting, Institut
                       Laue-Langevin (ILL) located on the
                       European Photon and Neutron (EPN)
                       campus (France), 11 Dec 2024 - 13 Dec
                       2024},
      subtyp        = {Invited},
      cin          = {JCNS-2 / JARA-FIT / JCNS-ILL},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / $I:(DE-82)080009_20140620$ /
                      I:(DE-Juel1)JCNS-ILL-20110128},
      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},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/1034060},
}