Linear Magnetic Birefringence Research Articles

Erratum: Waveguide mode conversion by magnetic linear birefringence of Bi-substituted iron garnet films tilted from (111) [J. Appl. Phys. 5 7, 718 (1985)

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Refractive index and birefringence measurements of the short-range order in the one-dimensional Heisenberg ferromagnet CsNiF3

Magnetic short-range order in the one-dimensional Heisenberg ferromagnet CsNiF3 has been investigated by linear magnetic birefringence and optical phase retardation measurements The short-range order was found to extend beyond 120K. The contributions of out-of-plane fluctuations and of the interchain interaction have been recognised. The values of the photoelastic coefficients and of the lattice dilatations are also reported.

Waveguide mode conversion by magnetic linear birefringence of Bi-substituted iron garnet films tilted from (111)

TE-TM mode conversion caused by magnetic linear birefringence (MLB) has been studied in liquid-phase-epitaxially grown (BiGdLu)3 (FeGa)5O12 films. The films were grown on Gd3Ga5O12 substrates of which the face normal is tilted from the (111) axis by the angle θc. The LPE growth on the substrate with θc ≠0 made the magnetization of the film tilt from the film normal, and this enabled the mode converter to work without any applied external field. The theory developed to describe the function of the mode converter agreed well with the experimental results. The MLB coefficient is about −9 rad/cm at a wavelength λ=1.15 μm. The Bi substitution is effective to enhance the MLB effect. A role of the MLB mode converter to realize a simple and compact waveguide optical isolator is discussed.

Magnetic Vortex Dynamics Using the Optical Cotton-Mouton Effect

The first use of linear magnetic birefringence (optical Cotton-Mouton effect) to observe a magnetic resonance is reported. This allows us to make the first direct observation of resonant motion of a ferromagnetic vortex. This vortex is present in an easy-plane garnet film at the intersection of two 90\ifmmode^\circ\else\textdegree\fi{} N\'eel walls. Agreement between the resonant frequencies and our theory confirms a previously proposed equation of vortex motion.

Magneto-optic observation of Bloch lines

We report the first visual observation of Bloch lines in thin garnet films without the perturbing influence of magnetic particles in suspension (Bitter solution). A second-order magneto-optic effect reveals the Bloch line position and the signs and positions of the domain wall segments lying adjacent to it. The present study is limited to Neel walls that separate in-plane domains aligned along [110] ‘‘easy’’ magnetic axes in a (100) garnet film 0.8 μm thick with large in-plane uniaxial anisotropy (Ku≪0). Images are viewed using normally incident laser illumination and crossed polarizers in a polarizing microscope also having an adjustable optical phase compensator. The contrast image for 180° walls with incident light vector E∥ polarized parallel to the wall is an adjacent pair of dark and light stripes. The usual first-order Faraday effect (magnetic circular birefringence) is excluded because all components of M are perpendicular to the beam. The quadratic dependence on M is verified, outside the wall at least, in domain contrast studies, e.g., by the lack of contrast between two opposing 180° domains. Within the wall magnetic linear birefringence would cause incident light E∥ to emerge as right- or left-handed elliptically polarized light according to the quadrants of the orientation of M wall in the E∥−E⊥ plane. Thus, the observed ordering of black/white or white/black stripes in the image reflects the sign of twist in M wall when the transmitted light is viewed through a compensator and analyser. The Bloch-line position is delineated by a discontinuous reversal in the black/white ordering.

High Field Diamagnetic Susceptibility and the “Curie-Weiss Law” in Organic Liquid

High field diamagnetic susceptibility of organic liquids is measured by means of linear magnetic birefringence (Cotton-Mouton effect) in pulsed high magnetic field up to 400 kOe with special interest in the temperature dependence. It is found that the “Curie-Weiss law” should widely be applied for the high field diamagnetic susceptibility of organic liquids consisted of anisotropic diamagetic molecules. The “Curie-Weiss constant” \(\varTheta\) reflects the intermolecular correlation in liquids and the obtained values are 0, 145 and 165 K for benzene, chlorobenzene and nitrobenzene, respectively.

Critical behavior of the magnetization of K 2CuF 4 and Rb 2CrCl 4 a comparative magneto-optical study

The temperature and field dependent magnetization of the quasi-2D ferromagnets K 2CuF 4 and Rb 2CrCl 4 is measured near T c within the easy c planes using linear magnetic birefringence. Scaled plots of M/H 1/δ i versus ∈/ H 1/βδ i exhibit 3D XY critical behavior for K 2CuF 4, whereas Rb 2CrCl 4 is nearly tricritical crossing over to 3D Ising below T c.

Phenomenological analysis of the linear magnetic birefringence in dysprosium iron garnet

In dysprosium iron garnet, the linear magnetic birefringence measured at 1.15 μm wavelength is analyzed in terms of electric dipole transitions. The 2nd order magneto-optical (MO) coefficient of the Dy 3+ ions is strongly temperature and magnetic field dependent as previously found for the 1st order (MO) coefficient.

Magnetooptics and its uses

This review is concerned with recent work on magnetooptics in magnetic materials. Primarily it is organized around magnetooptical (MO) rotation, magnetic linear birefringence and light scattering from magnetic excitations. Examples are quoted of work using each of these to study such properties as magnetic ordering, magnetic transitions, magnetic specific heat in random systems and elementary excitations in regular and random systems. Beyond the phenomena themselves and their research applications, there has been a continuing interest in technological applications. Interesting examples of these will be sketched briefly.

Phenomenological analysis of the linear magnetic birefringence in dysprosium iron garnet

Experimental data on linear magnetic birefringence (LMB), previously reported at 1.15 μm wavelength in the 4.2-300 K temperature range and with an applied field up to 20 kOe, in dysprosium iron garnet (DyIG) are analyzed in terms of electric dipole transition within the three magnetic sublattices. Assuming that the garnet symmetry is cubic and that the contribution of the Fe3+ ions to LMB is the same as yttrium iron garnet (YIG), the 2nd order magneto-optical (MO) coefficient (Γ2) of the Dy3+ ions is deduced. In the spontaneous state, Γ2 is linear temperature dependent as previously found for the 1st order (MO) coefficient. It is shown that Γ2 must be field dependent to explain the evolution of the LMB.

Experimental study of the linear magnetic birefringence in erbium iron garnet

Linear magnetic birefringence (Cotton-Mouton effect) and optical axis position have been measured in Er3Fe5O12 crystals in the Voigt geometry in the 10–300 K temperature range. Deviation of the optical axis away from the magnetic field direction is found below the compensation temperature, when the magnetic field is not applied along the easy axis of magnetization [100]. Cotton-Mouton effect evolution is reported and compared with that of YIG and with magnetization of ErIG. A large anisotropy of ErIG Cotton-Mouton effect is observed, with sign of the slopes of Cotton-Mouton effect versus field depending on the field orientation.

Critical behavior in random anisotropic antiferromagnets

The role of random uniaxial anisotropy on critical behavior has been studied in the antiferromagnetic system FexMn1−xF2 using linear magnetic birefringence. In the pure FeF2 and MnF2 crystals the deduced magnetic specific heat near TN shows no rounding for reduced temperature t as small as 10−4. Except for the effects of concentration gradients, no rounding is observed in the mixed crystals. In fact, for the Fe.75 Mn.25F2 sample, where such gradient effects are minimal, the transition is as sharp as in pure FeF2. Since MnF2 and FeF2 differ primarily in the size of the single ion anisotropy, it is clear that random anisotropy, by itself, does not broaden the transition. If anisotropy were not considered, MnF2 and FeF2 would be expected to have nearly identical TN. Although MnF2 is itself asymptotically Ising-like as T→TN because of its small but finite anisotropy, the larger TN in the more anisotropic FeF2 and the drastic increase in TN with x near x = 0 is attributable to the effects of crossover from Heisenberg to Ising critical behavior.

Sublattice contributions to second-order magneto-optical effects in rare-earth iron garnets

The angular variation of second-order magnetooptical effects, as the crystal is rotated relative to the magnetization, is calculated for each sublattice of rare-earth iron garnets. The expressions are obtained by applying Tucciarone's recently proposed AVIA (angular variation of induced anisotropy) method, which, in the approximation of axially symmetric garnet sites, gives the angular variation of a general garnet anisotropy property. The octahedral contribution vanishes when the magnetization lies along fourfold crystal axes, whereas the tetrahedral contribution vanishes when the magnetization lies along threefold axes or at an angle of 45° with respect to fourfold axes. All sublattice contributions are found to have in shape the same angular variation. The data of previous experiments are compared with theory and agree well with this behavior. On the basis of the theoretical expressions it is possible to analyze tha data and to distinguish, at different wavelengths and temperatures, the contributions to magnetic linear dichroism and birefringence coming from different sublattices. Finally, theory allows a new and simple interpretation for phenomenological macroscopical parameters, which were previously introduced in order to describe the crystallooptical behavior of cubic magnetic materials.

Magneto-optical properties of the two-dimensional ferromagnet K2CuF4. II. Linear magnetic birefringence

For pt.I see ibid., vol.12, p.2671 (1979). Presents data on the temperature and the magnetic field dependence of the linear magnetic birefringence (LMB) of the two-dimensional ferromagnet K2CuF4. The LBM appears spontaneously in the (ac) plane or can be induced by an external field within the (a,a) plane. The dependence of the LMB on the direction of the magnetisation is analysed in terms of a phenomenological theory. The vanishing of the magneto-optical constant rho 66 is explained within the framework of a microscopic theory. This accounts for anisotropic exchange due to the Jahn-Teller distortion of the CuF6 octahedra within the basal plane. The observed proportionalities Delta naa varies as M2 and ( Delta nac)m varies as Emagn and the dispersion of Delta naa are essentially confirmed and critically discussed.

Linear magnetic birefringence and double-excitonic transitions of the two-dimensional antiferromagnet BaNiF4

The temperature dependence of the linear birefringence (LB) of BaNiF4 as measured between 5 and 600K proves to be identical for the (a,c), (b,c) and (a,b) planes. In agreement with a microscopical theory the LB consists of two terms being proportional to the energies of the lattice and of the nearly-two-dimensional Heisenberg spin system, respectively. By use of cp data of BaZnF4 and of high-temperature series expansion data of cm the complete cm curve is quantitatively derived from d mod Delta nac mod /dT and critically compared with results from caloric measurements. The T2 dependence at low temperatures is consistent with spin-wave theory. The 3D anomaly at TN=68.4K has a logarithmic divergence as a consequence of the crossover from 2D H to 2D I behaviour near tau =0.04. Essentially the same temperature dependence as for the LMB results for the intensity of double excitonic transitions in the near UV in agreement with the theory of Fujiwara et al. (1972). The transitions are identified by use of the single-exciton absorption spectrum being measured at LHeT and analysed in terms of the cubic crystal field scheme.

Magnetic Linear Dichroism and Birefringence of FeBO3 in the 6A1g → 4T1g Transition Region

physica status solidi (b)Volume 106, Issue 2 p. K127-K130 Short Note Magnetic Linear Dichroism and Birefringence of FeBO3 in the 6A1g → 4T1g Transition Region Yu. M. Fedorov, Yu. M. Fedorov L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this authorA. A. Leksikov, A. A. Leksikov L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this authorA. E. Aksyonov, A. E. Aksyonov L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this authorI. S. Edelman, I. S. Edelman L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this author Yu. M. Fedorov, Yu. M. Fedorov L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this authorA. A. Leksikov, A. A. Leksikov L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this authorA. E. Aksyonov, A. E. Aksyonov L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this authorI. S. Edelman, I. S. Edelman L. V. Kirenskii Institute of Physics, Academy of Sciences of the USSR, Siberian Branch, Kranoyarsk Search for more papers by this author First published: 1 August 1981 https://doi.org/10.1002/pssb.2221060249Citations: 7 660036 Krasnoyarsk, USSR. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume106, Issue21 August 1981Pages K127-K130 RelatedInformation

Linear magnetic birefringence in thin cobalt films

Linear magnetic birefringence in thin cobalt films

A refined study of the [111] magnetoelastic properties of terbium iron garnet: Relation to the cotton mouton birefringence

Accurate measurement of the γe, 2 magnetostriction constant of a single crystal of TbIG has been performed from 90 K up to the Neel temperature. Both spontaneous and forced magnetostriction differ markedly from the one ion model predictions. Moreover, the forced magnetostriction modulus is much stronger below the compensation temperature than expected from extrapolating the high temperature variations. The spontaneous [111] linear magnetic birefringence and its field derivative exhibit thermal variations proportional respectively to those of the spontaneous and forced magnetostriction from 80 to 200 K.

Dilution effects on TN and SRO in MnxZn1−xF2 and FexZn1−xF2

Measurements of the temperature derivative of the linear magnetic birefringence have been used to study the effects of dilution on the Néel temperature and the short range order in the antiferromagnetic rutile systems MnxZn1−xF2 and FexZn1−xF2.

Magnetic and optical properties of the layer type magnets (CH 2) 2(ND 3) 2MnCl 4 and (CH 2) n(NH 3) 2CuCl 4, n = 2, 3, 5

The magnetic and optical properties of the layer-type magnets (CH 2) 2(ND 3) 2MnCl 4 and (CH 2) n (NH 3) 2CuCl 4, n = 2, 3, 5, have been investigated. These compounds consist of layers of corner sharing chlorine octahedra which surround the magnetic metal ions. Adjacent layers are connected by covalent bonds. A complete picture of the magnetic properties could be obtained by the combination of magnetization and susceptibility measurements together with measurements of the optical absorption and the linear birefringence, in particular the linear magnetic birefringence (LMB). For (CH 2) 2(ND 3) 2MnCl 4 which has an antiferromagnetic interaction within the layers, the two dimensional (2-d) Heisenberg S = 5 2 antiferromagnet represents a very good approximation. The magnetic specific heat (as measured by the LMB) did not show any deviations from the ideal model. The Cu compounds consist of antiferromagnetically coupled ferromagnetic layers and show an entirely different behaviour. Very accurate measurements of the linear birefringence for (CH 2) 2(NH 3) 2CuCl 4 indicate a pronounced anomaly in the magnetic specific heat. This points to a 3-d magnetic behaviour also above the Néel temperature TN ≈ 34 K, which is corroborated by the magnetic measurements. This contrasts markedly with the behaviour previously found for the compound (CH 3NH 3) 2CuCl 4, which has pronounced 2-d properties. The reason for this “anomalous” behaviour could be found in a different superexchange path connecting Cu ions in adjacent layers in the di-ammonium salts, which involves two Cl anions (Cu-Cl-Cl-Cu), and is therefore more favorable than in the mono-ammonium salts. This exchange path implies a very strong dependence of the interlayer coupling on the distance between adjacent layers. In fact we have measured critical temperatures of 14.9 K and 7.6 K for the compounds (CH 2) 3(NH 3) 2CuCl 4 and (CH 2) 5(NH 3) 2CuCl 4, respectively. For the first time the LMB was used to measure a magnetic phase diagram, namely the one of (CH 2) 3(NH 3) 2CuCl 4. The critical exponent of the sublattice magnetization could be determined from the phase boundary at which the system enters the paramagnetic phase from the spin flop phase. Its “three dimensional” value β = 0.31 ± 0.02 is in accordance withthe theory of lattice dimensionality crossovers. Such crossovers are also observed by comparing the susceptibility curves of the different Cu salts.