Unusually large magnetic moment and tricritical behavior of the CMR compound NaCr2 O4 revealed with high resolution neutron diffraction and μ + SR
Journal article, 2023
The mixed valence Cr3+/Cr4+ compound NaCr2O4, hosts a plethora of unconventional electronic properties. In the present study, muon spin rotation/relaxation ( μ + SR) and high-resolution time-of-flight neutron powder diffraction measurements were carried out on high-quality samples to clarify the complex magnetic ground state of this unique material. We identified a commensurate canted antiferromagnetic order (C-AFM) with a canting angle of the Cr spin axial vector equal to θ c = ( 8.8 ± 0.5 ) ∘ , and an estimated Cr moment μ C r C ∼ ( 4.30 ± 0.01 ) μ B . Such an unusually large value of μ C r C is compatible with the existence of high-spin Cr sites created by the presence of an unconventional negative charge transfer state in NaCr2O4. In addition to the C-AFM structure, a novel magnetic supercell was also revealed. Such supercell display an incommensurate (IC)-AFM propagation vector (0 0 1 2 − δ ), having a Cr moment μ C r I C = ( 2.20 ± 0.03 ) μ B . It is suggested that the C-AFM and IC-AFM modulations have two different electronic origins, being due to itinerant and localized contributions to the magnetic moment respectively. Finally, the direct measurement of the magnetic order parameter for the C-AFM structure provided a value of the critical exponent β = 0.245 ≈ 1 4 , suggesting a non conventional critical behavior for the magnetic phase transition in NaCr2O4
muon spin rotation
neutron diffraction
colossal magnetoresistance
unconventional magnetism
Author
E. Nocerino
AlbaNova University Center
Ola Kenji Forslund
Chalmers, Physics, Materials Physics
Hiroya Sakurai
National Institute for Materials Science (NIMS)
Akinori Hoshikawa
Ibaraki University
Nami Matsubara
AlbaNova University Center
Daniel Andreica
Babeș-Bolyai University
Anton Zubayer
Linköping University
F. Mazza
Vienna University of Technology
Takashi Saito
High Energy Accelerator Research Organization
Jun Sugiyama
Comprehensive Research Organization for Science and Society (CROSS)
Japan Atomic Energy Agency
I. Umegaki
High Energy Accelerator Research Organization
Yasmine Sassa
Chalmers, Physics, Materials Physics
Martin Månsson
AlbaNova University Center
JPhys Materials
2515-7639 (eISSN)
Vol. 6 3 035009Realization of Novel Low‐Dimensional Skyrmion Systems
Swedish Research Council (VR) (2017-05078), 2019-06-01 -- 2021-12-31.
Areas of Advance
Materials Science
Subject Categories (SSIF 2011)
Condensed Matter Physics
DOI
10.1088/2515-7639/acdf21