Showing papers by "Sheldon Schultz published in 1989"
TL;DR: In this article, magnetic-susceptibility and magnetization measurements on single crystals of the CuO2-planar compound Gd2CuO4 indicate copper moment ordering near 260 K, producing an internal field at the gadolinium site that induces substantial anisotropy in the magnetic response.
Abstract: Magnetic-susceptibility and magnetization measurements on single crystals of the CuO2-planar compound Gd2CuO4 indicate copper moment ordering near 260 K, producing an internal field at the gadolinium site that induces substantial anisotropy in the magnetic response. Dilute substitutions for gadolinium and copper leave the essential physics unaffected. We suggest that copper ordering also occurs in Eu2CuO4 on the basis of substitutional studies but is not detected in other rare-earth-based compounds in this series. Rare-earth size appears to play an important role. © 1989 The American Physical Society.
99 citations
TL;DR: In this paper, the temperature dependence of the magnetic susceptibility is predicted in terms of the Boltzmann population of the excited multiplets, and a comparison with experimental data up to 350 K is made.
Abstract: Magnetic susceptibility measurements have shown anisotropic Van Vleck paramagnetism in ${\mathrm{Eu}}_{2}$${\mathrm{CuO}}_{4}$ single crystals. This behavior is associated with the singlet ground state ${(}^{7}$${\mathrm{F}}_{0}$) of ${\mathrm{Eu}}^{3+}$ ions, and the measured anisotropy is related to a crystal-field splitting of the excited multiplets ${(}^{7}$${\mathrm{F}}_{\mathrm{J}}$). From the experimental data at low temperatures (T\ensuremath{\lesssim}50 K) a crystal-field parameter ${A}_{2}^{0}$〈${r}^{2}$〉=-93(5) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and a spin-orbit coupling constant \ensuremath{\zeta}=303(15) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ have been estimated. The temperature dependence of the magnetic susceptibility is predicted in terms of the Boltzmann population of the excited multiplets, and a comparison with experimental data up to 350 K is made. The possibility of a magnetic contribution arising from the Cu ions is discussed in connection with some discrepancies observed between the experimental and calculated magnetic susceptibilities.
31 citations
TL;DR: In this article, the EPR, microwave absorption, and dc magnetization measurements were made on single crystals of the form R 2 CuO 4, which are the host compounds for the newly discovered series of electron cuprate superconductors.
11 citations
TL;DR: In this paper, the effect of magnetic viscosity on the angular dependence of a coercive field, H/sub c/, was measured as a function of the angle of the applied field for IBM 3480 CrO/sub 2/ tape, JVC Super-VHS Co- gamma Fe/Sub 2/O/Sub 3/ tape and a 0.3 mu m Co-Cr film with perpendicular anisotropy, at 4.2 K, 77 K and 300 K.
Abstract: In order to demonstrate the effect of magnetic viscosity on the angular dependence of a coercive field, H/sub c/, the authors measured H/sub c/ as a function of the angle of the applied field for IBM 3480 CrO/sub 2/ tape, JVC Super-VHS Co- gamma Fe/sub 2/O/sub 3/ tape, and a 0.3 mu m Co-Cr film with perpendicular anisotropy, at 4.2 K, 77 K, and 300 K. The data are compared to the numerical simulation of a modified Stoner-Wohlfarth model which includes thermally activated reversals of the magnetic moments of an ideal assembly of particles. The model suggests that, as temperature increases, H/sub c/ is reduced by a larger factor when the angle between the applied field and the alignment direction is small. Experimental evidence for this behavior is found in the CrO/sub 2/ and Co-Cr samples. It is concluded that, for some common magnetic recording media magnetic viscosity effects must be evaluated before one can infer a magnetization reversal mechanism from H/sub c/ vs. angle data. >
10 citations
TL;DR: In this article, a preparation procedure for Tl-Ba-Ca-Cu-O superconducting samples which can be levitated above or beneath a magnet is described and X-ray powder diffraction data for these samples are presented and discussed.
Abstract: A preparation procedure for the Tl-Ba-Ca-Cu-O superconducting samples which can be levitated above or beneath a magnet is described. X-ray powder diffraction data for these samples are presented and discussed. Their electronic and magnetic properties are presented. The explanation for the unusual levitation is briefly discussed.
2 citations