Nobuyuki Abe

Ferroelectric Polarization Flop in a Frustrated Magnet MnWO 4 Induced by a Magnetic Field

The relationship between magnetic order and ferroelectric properties has been investigated for MnWO

Interferon Induction by Glycyrrhizin and Glycyrrhetinic Acid in Mice

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Ferroelectric Polarization Reversal by a Magnetic Field in Multiferroic Y-type Hexaferrite Ba2Mg2Fe12O22

with long-wavelength magnetic structure. Spontaneous electric polarization is observed in an elliptical spiral spin phase. The magnetic-field dependence of electric polarization indicates that the noncollinear spin configuration plays a key role for the appearance of ferroelectric phase. An electric polarization flop from the b direction to the a direction has been observed when a magnetic field above 10T is applied along the b axis. This result demonstrates that an electric polarization flop can be induced by a magnetic field in a simple system without rare-earth f-moments.

Orbital dilution effect in ferrimagnetic Fe1 ? xMnxCr2O4: competition between anharmonic lattice potential and spin?orbit coupling

Licorice extract is an herbal drug which has long been used as a demulcent and elixir in Chinese medicine. One of the main active components of licorice extract is glycyrrhizin (GL), a kind of saponin. The biological effects of GL and its aglycone, glycyrrhetinic acid (GA), have been extensively studied. Their anti-inflammatory (5), anti-ulcerous (3), and antiviral (14) effects have been reported from 1948 (15) to 1979 (14). Moreover, a preparation of GL combined with glycine and cysteine (SNMC), has been widely and successfully used in Japan as an antihepatitis drug (6, II, 19), although its mechanism of pharmacological action remains unclear. Recently, interferon (IFN) with or without adenine arabinoside (Ara-A) has been used to treat hepatitis B patients (4, 7). Studies show that IFN consistently decreases the level of either DNA polymerase or hepatitis B surface antigen in hepatitis patients. There are also many reports which suggest that some irnmunopotentiators induce IFN (13) and explain their antiviral activity in vivo as interferon mediated (8, 16, 18). Therefore, in the light of GLs clinical effect on hepatitis patients and of the fact that its structure resembles that of hydrocortisone, the possibility that GL induces IFN was proposed. In this study we investigated the ability of both GL and GA to induce IFN in mice. Sixto 8-week-old male DDI mice obtained from the Institute for Experimental Animals, Tohoku University School of Medicine, were used in this experiment. Six-week-old male C3H, ddY, CDF-l, C57BL, BALB/c, and athymic nude mice (nujnu) of BALB/c background were obtained from the Funabashi Farm Co., Ltd., and were used to study the effect of the different mouse strains on interferon induction. GL and GA were supplied by Minophagen Pharmaceutical Co. Drugs were dissolved in 0.01 M phosphate buffered saline (PBS) and adjusted to pH 7.2 with I N sodium hydroxide. Pooled sera obtained from three mice were tested for anti-viral activity, which was determined by the 50% plaque reduction method on L-929 monolayer cell cultures with vesicular stomatitis virus (VSV) and was expressed in international reference units based on NIH reference mouse IFN (Catalog No. 002-904-511) (12).

Magnetic shape memory effect in orbital-spin-coupled system MnV2O4

Coexistence of the ferroelectric polarization and spontaneous magnetization has been found in Y-type hexaferrite Ba2Mg2Fe12O22. The reversal of magnetization by a small magnetic field below ~0.02 T accompanies an electric polarization reversal through the clamping of ferrimagnetic and ferroelectric domain walls. This behavior can be potentially used as a magnetically rewritable ferroelectric memory and an electrically rewritable magnetic memory.

One-Way Transparency of Light in Multiferroic CuB 2 O 4

Magnetic and structural phase diagram in a spinel-type solid solution system Fe(1-x)Mn(x)Cr(2)O(4) has been investigated. The cubic-to-tetragonal transition temperature T(s 1) is gradually reduced by the substitution of Mn(2+) (3d(5)) for Jahn-Teller-active Fe(2+) (3d(6)) ions, implying the long-range nature of the ferroic interaction between orbitals. In the paramagnetic tetragonal phase for x < 0.5, the c parameter is shorter than a because of the anharmonicity of the elastic energy. The crystal structure further changes to orthorhombic at around the ferrimagnetic transition temperature T(N 1). T(s 1) and T(N 1) meet at x = 0.5, and Mn substitution of more than 0.5 gives rise to another tetragonal phase with a < c. The systematic change in crystal structure is discussed in terms of competition between the anharmonic lattice potential and the intra-atomic spin-orbit interaction at Fe(2+).

Visualization of ferroelectric domains in boracite using emission of terahertz radiation

Magnetic-field(H)-induced shape memory effect without temperature variation is demonstrated by a combination of H-sweep and H-rotation in an orbital-spin-coupled spinel-type insulating system MnV2O4. A rotation of the direction of a magnetic field of 5u2009T in the low-temperature tetragonal phase gives rise to a large macroscopic strain up to 1%, which stems from a 90° rotation of tetragonal domains. The results show several possible ways of macroscopic shape control in this class of matter, and may open a possibility of high-speed actuators free from the eddy current.

Magnetic-field effects on Jahn-Teller distortion in ferroelastic magnetic insulator Fe1−xMnxCr2O4

We experimentally demonstrate one-way transparency of light in multiferroic CuB(2)O(4). The material is rendered transparent for light propagating in one direction, while opaque for light propagating in the opposite direction. The novel transparency results from a destructive interference of the electric dipole and magnetic dipole transitions. The realization of the effect has been accomplished by the application of a high magnetic field and the proper selection of the propagation direction of light in agreement with our quantum mechanical formulation of nonreciprocal directional dichroism.

Observation of Spin Helicity Using Nonresonant Circularly Polarized X-ray Diffraction Analysis

We report on the emission of terahertz radiation by irradiation of femtosecond laser pulses in non-centrosymmetric paraelectric and ferroelectric phases of Co

Control of the polarization flop direction in multiferroic RMnO3 (R = Tb, Dy) by a tilted magnetic field

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