title: Structural modulation in the orbitally induced Peierls state of MgTi(2)O(4).
abstract: The structural properties associated with the orbitally induced Peierls transition in MgTi(2)O(4) are characterized by in situ cooling TEM observations. A distinctive structural modulation with the wavevector of q(1) = 1/4 (0, 0, 4) has been well demonstrated below a critical temperature of about 260 K for MgTi(2)O(4). Systematic analysis demonstrates that this structural modulation can be well explained by an orbital order existing in the low-temperature insulating phase. It is also noted that the nonstoichiometric feature commonly appearing in the present system could yield visible changes in both physical and structural properties. A low-temperature study of the microstructure of Mg[Ti(1.9)Mg(0.1)]O(4) reveals that a little substitution of Mg(2+) for Ti(3+) ions on the octahedral sites can disrupt the long-range order of the t(2g) orbitals, resulting in complex tweed structures in the superstructure phase.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
authors.forename: H X
authors.initials: HX
authors.lastname: Yang
authors.forename: B P
authors.initials: BP
authors.lastname: Zhu
authors.forename: L J
authors.initials: LJ
authors.lastname: Zeng
authors.forename: H F
authors.initials: HF
authors.lastname: Tian
authors.forename: C
authors.initials: C
authors.lastname: Ma
authors.forename: J
authors.initials: J
authors.lastname: Shi
authors.forename: J Q
authors.initials: JQ
authors.lastname: Li