Orbital ordering transition in Ca{sub 2}RuO{sub 4} observed with resonant x-ray diffraction.

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Phys. Rev. Lett.

DOI:https://doi.org/10.1103/PhysRevLett.95.136401· OSTI ID:925296

Zegkinoglou, I; Strempfer, J; Nelson, C S; Hill, J P; Chakhalian, J; Bernhard, C; Lang, J C; Srajer, G; Fukazawa, H; Nakatsuji, S; Maeno, Y; Keimer, B; BNL,

Resonant x-ray diffraction performed at the LII and LIII absorption edges of Ru has been used to investigate the magnetic and orbital ordering in Ca{sub 2}RuO{sub 4} single crystals. A large resonant enhancement due to electric dipole 2p-->4d transitions is observed at the wave-vector characteristic of antiferromagnetic ordering. Besides the previously known antiferromagnetic phase transition at T{sub N}=110 K, an additional phase transition, between two paramagnetic phases, is observed around 260 K. Based on the polarization and azimuthal angle dependence of the diffraction signal, this transition can be attributed to orbital ordering of the Ru t{sub 2g} electrons. The propagation vector of the orbital order is inconsistent with some theoretical predictions for the orbital state of Ca{sub 2}RuO{sub 4}.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; FOR
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 925296
• Report Number(s): ANL/XFD/JA-54903
• Journal Information: Phys. Rev. Lett., Journal Name: Phys. Rev. Lett. Journal Issue: 13 ; 2005 Vol. 95; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
CALCIUM OXIDES
ELECTRONIC STRUCTURE
MAGNETIC PROPERTIES
MONOCRYSTALS
ORDER PARAMETERS
PHASE TRANSFORMATIONS
RUTHENIUM OXIDES
X-RAY DIFFRACTION