摘要:

New experiments in the far infrared on the AFMR node in ferrous chloride revealed the appearance of structure of increasing complexity with rising temperature 1.3 K <T<18 K). At temperatures above 8 K we observe on the lower energy side the progressive growth of new peaks distributed in an energy band of about 10 cm−1. We propose an explanation of this structure in terms of a cluster model taking into account only nearest neighbor interactions. The observed peaks would then arise from transitions starting from thermally populated levels corresponding to different spin arrangements of the neighbors.

ISSN:0021-8979    

DOI:10.1063/1.324729

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The absorption spectrum of oxygen‐annealed Fe3BO6in the range 4000–18000 cm−1is examined in terms of polaronic absorption and crystal field transitions. Some absorption lines at the onset of the4T1band have been investigated in a magnetic field making possible their unambiguous identification and an assignment to the two distinct iron sites of Fe3BO6. The measurements yield insight into details of the spin structure and the field‐dependent spin reorientation occurring in Fe3BO6.

ISSN:0021-8979    

DOI:10.1063/1.324730

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The existence of a ferromagnetic surface layer in antiferromagnetic chromium has been confirmed experimentally by detecting surface magnetoplasma waves (SMPW) via the method of attenuated total reflection. The optical configuration consisted of a half cylinder heavy dense flint prism −900 A˚ MgF2dielectric thin film–optically opaque chromium film. The dispersion curve for surface plasma waves (SPW) was obtained by measuring the reflectivity as a function of angle of incidence at constant photon energy in the range of 2.0–4.0 eV. Measurement of the normalized reflectivity difference &dgr; due to a low frequency oscillating magnetic field applied perpendicular to the direction of propagation of the SPW indicates the presence of SMPW and therefore a ferromagnetic surface layer. Experimentally &dgr; maximizes atE=3.25 eV and varies linearly with the applied magnetic field to 500 Oe. In the absence of SPMW &dgr; is less than 1&percent; of the &dgr; measured in the presence of SMPW in the same photon energy range.

ISSN:0021-8979    

DOI:10.1063/1.324731

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The linear birefringence (LB) of the layered antiferromagnet (CH2)2(ND3)2CuCl4was measured in several crystallographic directions as a function of temperature, wavelength and magnetic field. The index ellipsoid rotates upon cooling around the monocliniczaxis. The temperature derivative of the LB, corresponding to the specific heat, when measured perpendicularly to the layers, shows a pronounced anomaly atTN=34.24±0.05 K. The nearly ideal 2‐dimensional behavior encountered in the related compound (C2H5NH3)2CuCl4is completely lost by the covalent inter layer coupling. The LB shows only a weak dependence on an applied magnetic field; however, the spin flop transition can be seen unambiguously atHSF=9.3±0.5 kOe (T=2 K). No Faraday effect could be observed as yet.

ISSN:0021-8979    

DOI:10.1063/1.324732

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The magnetic, optical, and magneto‐optical behavior of the crystals LiTbF4, LiTb0.5Y0.5F4, LiTb0.25Gd0.75F4, and KTb3F10have been measured. We present the temperature, wavelength, and magnetic field dependence of the Faraday rotation in these materials and the wavelength dependence of the optical absorption. The magnetic ordering found in these crystals and its relation to optical phenomena is also discussed.

ISSN:0021-8979    

DOI:10.1063/1.324733

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

An analysis of polar Kerr rotation (PKR) spectra of diamagnetically substituted Y3Fe5O12(YIG) is proposed using the relation 2&fgr;K=aA(&ohgr;)+bB(&ohgr;) where &fgr;Kis the PKR in min,aandbare the coefficients proportional to the magnetic moments of the octahedral and tetrahedral sublattices,A(&ohgr;) andB(&ohgr;) coefficients calculated from the PKR spectra of both YIG and lithium ferrite using the above relation. In this manner the spectral dependences of PKR both for the tetrahedral and octahedral diamagnetic substitution are calculated and the results compared with the experiment.

ISSN:0021-8979    

DOI:10.1063/1.324734

出版商:AIP    

年代:1978

数据来源: AIP