Observation of a multiferroic critical end point.
The study of abrupt increases in magnetization with magnetic field known as metamagnetic transitions has opened a rich vein of new physics in itinerant electron systems, including the discovery of quantum critical end points with a marked propensity to develop new kinds of order. However, the electric analogue of the metamagnetic critical end point, a "metaelectric" critical end point, has been rarely studied. Multiferroic materials wherein magnetism and ferroelectricity are cross-coupled are ideal candidates for the exploration of this novel possibility using magnetic-field (H) as a tuning parameter. Herein, we report the discovery of a magnetic-field-induced metaelectric transition in multiferroic BiMn(2)O(5), in which the electric polarization (P) switches polarity along with a concomitant Mn spin-flop transition at a critical magnetic field H(c). The simultaneous metaelectric and spin-flop transitions become sharper upon cooling but remain a continuous cross-over even down to 0.5 K. Near the P = 0 line realized at mu(0)H(c) approximately 18 T below 20 K, the dielectric constant (epsilon) increases significantly over wide field and temperature (T) ranges. Furthermore, a characteristic power-law behavior is found in the P(H) and epsilon(H) curves at T = 0.66 K. These findings indicate that a magnetic-field-induced metaelectric critical end point is realized in BiMn(2)O(5) near zero temperature.
Kim
Jae Wook
JW
Center for Strongly Correlated Materials Research and Frontier Physics Research Division, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, South Korea.
Haam
S Y
SY
Oh
Y S
YS
Park
S
S
Cheong
S-W
SW
Sharma
P A
PA
Jaime
M
M
Harrison
N
N
Han
Jung Hoon
JH
Jeon
Gun-Sang
GS
Coleman
P
P
Kim
Kee Hoon
KH