TY - JOUR
T1 - Soft tilt and rotational modes in the hybrid improper ferroelectric Ca3Mn2 O7
AU - Glamazda, A.
AU - Wulferding, D.
AU - Lemmens, P.
AU - Gao, B.
AU - Cheong, S. W.
AU - Choi, K. Y.
N1 - Funding Information:
This work was supported by Korea NRF Grants No. 2009-0093817 and No. 2017-012642, DFG Le967/16-1, DFG-RTG1953/1, Metrology for Complex Nanosystems, the NTH- School Contacts in Nanosystems: Interactions, Control and Quantum Dynamics, the Quantum- and Nano-Metrology (QUANOMET) initiative within project NL-4, and the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant No. GBMF4413 to the Rutgers Center for Emergent Materials.
Publisher Copyright:
© 2018 American Physical Society.
PY - 2018/3/14
Y1 - 2018/3/14
N2 - Raman spectroscopy is employed to probe directly the soft rotation and tilting modes, which are two primary order parameters predicted in the hybrid improper ferroelectric material Ca3Mn2O7. We observe a giant softening of the 107-cm-1 octahedron tilting mode by 26cm-1 on heating through the structural transition from a ferroelectric to paraelectric orthorhombic phase. This is contrasted by a small softening of the 150-cm-1 rotational mode by 6cm-1. In the intermediate phase, the competing soft modes with different symmetries coexist, bringing about many-faceted anomalies in spin excitations and lattice vibrations. Our work demonstrates that the soft rotation and tilt patterns, relying on a phase-transition path, are a key factor in determining ferroelectric, magnetic, and lattice properties of Ca3Mn2O7.
AB - Raman spectroscopy is employed to probe directly the soft rotation and tilting modes, which are two primary order parameters predicted in the hybrid improper ferroelectric material Ca3Mn2O7. We observe a giant softening of the 107-cm-1 octahedron tilting mode by 26cm-1 on heating through the structural transition from a ferroelectric to paraelectric orthorhombic phase. This is contrasted by a small softening of the 150-cm-1 rotational mode by 6cm-1. In the intermediate phase, the competing soft modes with different symmetries coexist, bringing about many-faceted anomalies in spin excitations and lattice vibrations. Our work demonstrates that the soft rotation and tilt patterns, relying on a phase-transition path, are a key factor in determining ferroelectric, magnetic, and lattice properties of Ca3Mn2O7.
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U2 - 10.1103/PhysRevB.97.094104
DO - 10.1103/PhysRevB.97.094104
M3 - Article
AN - SCOPUS:85043998182
VL - 97
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 0163-1829
IS - 9
M1 - 094104
ER -