TY - JOUR
T1 - Hyperferroelectrics
T2 - Proper ferroelectrics with persistent polarization
AU - Garrity, Kevin F.
AU - Rabe, Karin M.
AU - Vanderbilt, David
PY - 2013/12/1
Y1 - 2013/12/1
N2 - All known proper ferroelectrics are unable to polarize normal to a surface or interface if the resulting depolarization field is unscreened, but there is no fundamental principle that enforces this behavior. In this work, we introduce hyperferroelectrics, a new class of proper ferroelectrics which polarize even when the depolarization field is unscreened, this condition being equivalent to instability of a longitudinal optic mode in addition to the transverse-optic- mode instability characteristic of proper ferroelectrics. We use first-principles calculations to show that several recently discovered hexagonal ferroelectric semiconductors have this property, and we examine its consequences both in the bulk and in a superlattice geometry.
AB - All known proper ferroelectrics are unable to polarize normal to a surface or interface if the resulting depolarization field is unscreened, but there is no fundamental principle that enforces this behavior. In this work, we introduce hyperferroelectrics, a new class of proper ferroelectrics which polarize even when the depolarization field is unscreened, this condition being equivalent to instability of a longitudinal optic mode in addition to the transverse-optic- mode instability characteristic of proper ferroelectrics. We use first-principles calculations to show that several recently discovered hexagonal ferroelectric semiconductors have this property, and we examine its consequences both in the bulk and in a superlattice geometry.
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U2 - 10.1103/PhysRevLett.112.127601
DO - 10.1103/PhysRevLett.112.127601
M3 - Article
AN - SCOPUS:84897375322
SN - 0031-9007
VL - 112
JO - Physical review letters
JF - Physical review letters
IS - 12
M1 - 127601
ER -