TY - JOUR
T1 - Small crystal distortion and long-range antiferro-orbital ordering in the spinel oxide Co V2 O4
AU - Ishibashi, H.
AU - Shimono, S.
AU - Tomiyasu, K.
AU - Lee, S.
AU - Kawaguchi, S.
AU - Iwane, H.
AU - Nakao, H.
AU - Torii, S.
AU - Kamiyama, T.
AU - Kubota, Y.
N1 - Funding Information:
We thank Dr. H. Sagayama for his technical support in single crystal diffraction experiments. The neutron diffraction experiments using SuperHRPD were performed at BL08 in the MLF at J-PARC (Proposal No. 2014A0186). The synchrotron radiation experiments were performed at BL-4C and BL-8B, with the approval of the PF Program Committee (Proposals No. 2014G049 and No. 2012S2-005). This research was partially supported by KAKENHI (Grants No. JP16K04866, No. JP16K17548, No. JP15H03692, No. JP17H06137, No. JP16H04223, and No. JP16K14425) from the Japan Society for the Promotion of Science (JSPS) and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and by the FRIS Program for the creation of interdisciplinary research at Tohoku University.
Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/10/18
Y1 - 2017/10/18
N2 - In frustrated spinel oxide CoV2O4, the knowledge of orbital, lattice, and spin structures has been fragmentary thus far. To investigate the structural and magnetic phase transitions in CoV2O4, we performed high-resolution neutron powder diffraction, single crystal synchrotron radiation diffraction, and magnetization and specific heat measurements for high-quality samples. Extremely small crystal distortion from cubic to tetragonal phase (1-c/a<0.06%) was observed using the high-resolution neutron diffraction measurement below T∗∼95K, where a cusp was observed in the temperature dependence of magnetization. The single crystal diffraction experiment revealed that the structural phase transition accompanied by a change in the space group from I41/amd to I41/a occurred at T2=59K, where the phase transition was observed in the specific heat measurement. Crystal and magnetic structure analysis was carried out with the neutron data, and the results suggest that the magnetic phase transition from collinear to noncollinear magnetic ordering occurs at T∗ and the antiferro-orbital ordering occurs below T2. We discuss the observed small crystal distortion and orbital characteristics in the light of the boundary between localization and delocalization.
AB - In frustrated spinel oxide CoV2O4, the knowledge of orbital, lattice, and spin structures has been fragmentary thus far. To investigate the structural and magnetic phase transitions in CoV2O4, we performed high-resolution neutron powder diffraction, single crystal synchrotron radiation diffraction, and magnetization and specific heat measurements for high-quality samples. Extremely small crystal distortion from cubic to tetragonal phase (1-c/a<0.06%) was observed using the high-resolution neutron diffraction measurement below T∗∼95K, where a cusp was observed in the temperature dependence of magnetization. The single crystal diffraction experiment revealed that the structural phase transition accompanied by a change in the space group from I41/amd to I41/a occurred at T2=59K, where the phase transition was observed in the specific heat measurement. Crystal and magnetic structure analysis was carried out with the neutron data, and the results suggest that the magnetic phase transition from collinear to noncollinear magnetic ordering occurs at T∗ and the antiferro-orbital ordering occurs below T2. We discuss the observed small crystal distortion and orbital characteristics in the light of the boundary between localization and delocalization.
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U2 - 10.1103/PhysRevB.96.144424
DO - 10.1103/PhysRevB.96.144424
M3 - Article
AN - SCOPUS:85037682415
VL - 96
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 14
M1 - 144424
ER -