%A SHEN Xin-Chun, WANG Wen-Qing, GONG Yan, ZHANG Yan
%T Dynamical Spin Chirality and Magnetoelectric Effect of *α*-Glycine
%0 Journal Article
%D 2008
%J Acta Phys. -Chim. Sin.
%R 10.1016/S1872-1508(08)60081-9
%P 2153-2158
%V 24
%N 12
%U {http://www.whxb.pku.edu.cn/CN/abstract/article_21309.shtml}
%8 2008-12-04
%X Dynamical spin chirality of α-glycine crystal at 301-302 K was investigated by DC (direct current)-magnetic susceptibility measurement at temperatures ranging from2 to 315 Kunder the external magnetic fields (H=±1 T) parallel to the b axis. The α-glycine crystallizes in space group P21/n with four molecules in a cell, which has centrosymmetric charge distribution. The bifurcated hydrogen bonds N+(3)—H(8)…O(1) and N+(3)—H(8)…O(2) are stacked along the b axis with different bond intensities and angles, which formanti-parallel double layers. Atomic force spectroscopy result at 303 K indicated that the surface molecular structures of α-glycine formed a regular flexuous framework in the b axis direction. The strong temperature dependence is related to the reorientation of NH+3 group and the electron spin flip-flop of (N+H) mode. Under the opposite external magnetic field of 1 T and -1 T, the electron spins of N+(3)—H(8)…O(1) and N+(3)—H(8)…O(2) flip-flop at 301-302 K. These results suggested a mechanism of the magnetoelectric effect based on the dynamical spin chirality of (N +H), which induced the electric polarization to produce the onset of pyroelectricity of α-glycine around 304 K.