Ultrasonic attenuation study of erbium in a magnetic field

The ultrasonic attenuation coefficient of longitudinal waves propagating along the c-axis of a single crystal of erbium was measured over a temperature range which covers the transition temperature from the paramagnetic to the sinusiodal phase T₆ = 83.8 K and the transition temperature from the sinusoidal to elliptical phase T_⊥ = 53.9 K. These measurements were performed as a function of temperature in the presence of constant magnetic fields and at constant temperatures as a function of applied magnetic fields. A magnetic field parallel to the c-axis shifted T₆ to lower temperatures and reduced the peak attenuation. A broad new maximum emerged on the high temperature side of the field-shifted T₆. Application of H perpendicular to the c-axis produced little change in either T₆ or T_⊥. A model introduced by Tachiki and Mackawa is used to discuss the results.     

The temperature dependence of the magnetic hyperfine field of tantalum in dysprosium

The temperature dependence of the magnetic and electric hyperfine interactions at the site of ¹⁸¹Ta impurities in polycrystalline Dy has been measured between 4.2 and 178 K using the time differential perturbed angular correlation technique. The value of the magnetic hyperfine field at 4.2 K is: |H_hf(TaDy)| = 212(9) kG The temperature dependence of the magnetic hyperfine field follows closely the prediction of the molecular field model.     

Ultrasonic attenuation of aluminium in transverse magnetic field

The attenuation of longitudinal sound wave in Al single crystal in high transverse magnetic field has been calculated by 4-OPW approximation. The wave vector of the sound wave is parallel to [1$\text{1}$0] axis. In general, the result agrees well with Berre's experiment. The attenuation plotted against the magnetic field direction has 3 peaks which are explained in terms of the geometry of the Fermi surface of Al.     

Magnetic field induced intermediate state in dysprosium orthoferrite

The field induced spin reorientation in DyFeO₃ has been observed visually using the magneto-optical method. An intermediate state has been shown to exist between antiferromagnetic and weak ferromagnetic states. A simple model is proposed to calculate the static properties of phase domains.     

Spectroscopic study of a brush cathode plasma in a magnetic field

The brush cathode helium discharge in the magnetic field has been operated stably at discharge currents larger than those without magnetic field. The diameter of the plasma column has been determined by the configuration of the magnetic field. The measurements of the spectral intensities of the recombination continuum followed by the 2³S-n³P series reveals that the electron density is 1·8 × 10¹³ cm^-3 and the electron temperature is 0·17 eV at a discharge current of 500 mA and a pressure of 0·9 torr for a magnetic flux density of 1·3 kG. The principal quantum number for line merging is 20.     

Universal hysteresis scaling for incommensurate magnetic order in dysprosium

We study the scaling properties of magnetic minor hysteresis loops in a polycrystalline dysprosium metal, varying temperature and magnetic-field amplitudes. We observe irreversibility-related hysteresis loss in the helical antiferromagnetic phase, which is related with remanent flux density as a power law with the same scaling exponent of 1.25±0.05 as that in ferromagnetic materials. In contrast to hysteresis scalings in ferromagnets associated with 180° Bloch walls, the observed law is governed by spiral walls which separate helical domains with oppositely rotating spins.     

Investigations of the first order magnetic phase transition in dysprosium

The first order magnetic phase transition in polycrystalline sample of dysprosium (Dy) has been investigated in detail by dc-resistance vs. temperature (R-T) measurements. Distinct signature of coexistence of two magnetically ordered phases (i.e. ferromagnetic and antiferromagnetic), originating as a result of the metastable behavior associated with the first order phase transition (FOPT) is found near 90 K. By successfully recording the minor hysteresis loops within the hysteretic R-T regime of Dy, a varying degree of phase coexistence in the FOPT is demonstrated.     

Elasticity of a magnetic fluid in a strong magnetic field

Complex measurements of the following elastic-magnetic parameters of a magnetic fluid suspended by magnetic levitation within a horizontal tube in a strong magnetic field were performed: the oscillation frequency and decay coefficient; the static, ponderomotive, and dynamic elasticity coefficients; the fluid displacement under hydrostatic pressure; magnetization curve; and the magnetic field strength and gradient. Calculations based on a model of ponderomotive elasticity with correction for the resistance of a viscous fluid in motion and on the fluid column displacement for two magnetic fluid samples agree well with the experimental magnetization curve. The discussed technique holds promise for research into magnetophoresis and nanoparticle aggregation in magnetic colloids.     

Microscopic study of neutron-rich dysprosium isotopes

Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, γ and β bands, and their B(E2) transition strengths in ^160–168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q · Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of γ and β bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus ¹⁷⁰Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model.     

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.     

导磁导电球体在均匀谐变磁场中产生的磁场分布规律

从求解导磁导电各向同性球体的赫兹矢量π*出发,推导出了导磁导电球体置于均匀谐变低频弱磁场中球体产生的磁场分布规律和球频率函数.     

Experimental study of an argon laser discharge in a transverse magnetic field

Summary The influence of a static magnetic field orthogonal to the axis of an argon laser discharge is investigated. The enhancement of the small-signal gain at 488 nm is measured as a function of the magnetic field at different values of the parameters of the discharge. The data about the gain compared with the measurement of the fluorescence from the upper level of the 488 nm line give information about the excitation mechanisms. A strong enhancement of the ionization rate of Ar⁺ is detected.     

Theoretical study of a magnetoresistive magnetic field transmitter with a ring sensor

Theoretical results are presented concerning the performance of thin-film anisotropic magnetoresistive magnetic field sensors with a single- and multilayered ring configuration. A mathematical model is proposed that allows analytical calculation of magnetization fields, is suitable for sensor optimization, and requires a reasonable amount of computing time. A system of equations is derived for the magnetization angle of rotation. On this basis, the response, sensitivity, and angular characteristics of particular sensors are optimized.     

Chiral thermodynamics in a magnetic field

The phase structure of the QCD vacuum in a magnetic field H is investigated at low temperatures T. The free energy of the hadronic phase in a constant homogeneous magnetic field is calculated in the one-loop approximation of chiral perturbation theory. The quark and the gluon condensate are found as functions of temperature and the field strength. It is shown that the order parameter $\left\langle {\bar qq} \right\rangle $ for the chiral phase transition remains constant when the temperature T and the magnetic field H change in such a way that H=const×T ².     

Positronium interference in a magnetic field

The interaction of the positronium with a magnetic field is investigated. The high-precision formulae for probabilities of ortho-and parastates of the positronium in the magnetic field are calculated with allowance for the difference between the magnetic moments of electron and positron in positronium and those of free particles. The results of these calculations are used for setting up the PALM experiment dedicated to the parapositronium lifetime measurement in vacuum.     

Nonlinear surface magnetic polaritons in a nonuniform magnetic field

High-frequency surface magnetic polaritons of finite amplitude propagating along the interface between a ferrite and a nonlinear insulator in a weakly nonuniform, shaft-shaped external magnetic field are investigated theoretically. The analysis is based on employment of the variational method together with bilinear relations having the form of Lorentz’s lemma. It is shown that the wave dispersion and the transverse profile of a wave along the field nonuniformity depend significantly on the amplitude of the wave. Zh. Tekh. Fiz. 68, 92–95 (September 1998)