title: Spin-Driven Multiferroic Properties of PbMn7O12 Perovskite.
abstract: We synthesize PbMn7O12 perovskite under high-pressure (6 GPa) and high-temperature (1373 K) conditions and investigate its structural, magnetic, dielectric, and ferroelectric properties. We find that PbMn7O12 exhibits rich physical properties from interplay among charge, orbital, and spin degrees of freedom and rich structural properties. PbMn7O12 crystallizes in space group R3̅ near room temperature and shows a structural phase transition at TCO = 397 K to a cubic structure in space group Im3̅; the Im3̅-to-R3̅ transition is associated with charge ordering. Below TOO = 294 K, a structural modulation transition associated with orbital ordering takes place. There are two magnetic transitions with Néel temperatures of TN1 = 83 K and TN2 = 77 K and probably a lock-in transition at TN3 = 43 K (on cooling). There is huge hysteresis on specific heat (between ∼37 and 65 K at 0 Oe), dielectric constant (between ∼20 and 70 K at 0 Oe), and dc and ac magnetic susceptibilities around the lock-in transition. Sharp dielectric constant, dielectric loss, and pyroelectric current anomalies are observed at TN2, indicating that electric polarization is developed at this magnetic transition, and PbMn7O12 perovskite is a spin-driven multiferroic. Polarization of PbMn7O12 is measured to be ∼4 μC/m(2). Field-induced transitions are detected at ∼63 and ∼170 kOe at 1.6-2 K; similar high-magnetic field properties are also found for CdMn7O12, CaMn7O12, and SrMn7O12. PbMn7O12 exhibits a quite small magnetodielectric effect, reaching approximately -1.3 to -1.7% at 10 K and 90 kOe.
authors.affiliation: International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) , Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Belik
authors.affiliation: International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) , Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.|Department of Chemistry, Lomonosov Moscow State University , Leninskie Gory, 119992 Moscow, Russia.
authors.forename: Yana S
authors.initials: YS
authors.lastname: Glazkova
authors.affiliation: National Institute for Materials Science (NIMS) , Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Noriki
authors.initials: N
authors.lastname: Terada
authors.affiliation: National Institute for Materials Science (NIMS) , Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Matsushita
authors.affiliation: Department of Chemistry, Lomonosov Moscow State University , Leninskie Gory, 119992 Moscow, Russia.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Sobolev
authors.affiliation: Department of Chemistry, Lomonosov Moscow State University , Leninskie Gory, 119992 Moscow, Russia.
authors.forename: Igor A
authors.initials: IA
authors.lastname: Presniakov
authors.affiliation: National Institute for Materials Science (NIMS) , Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Naohito
authors.initials: N
authors.lastname: Tsujii
authors.affiliation: Tsukuba Magnet Laboratory, National Institute for Materials Science (NIMS) , 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Nimori
authors.affiliation: Tsukuba Magnet Laboratory, National Institute for Materials Science (NIMS) , 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan.
authors.forename: Kanji
authors.initials: K
authors.lastname: Takehana
authors.affiliation: Tsukuba Magnet Laboratory, National Institute for Materials Science (NIMS) , 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Imanaka