Field dependent specific heat study of the dipolar Ising ferromagnet LiHoF4

Magnetic and Thermal Properties of Tb(OH) 3

Single crystals of KTb3F10, LiTbF4, LiTb0.5Y0.5F4 and LiTb0.25Gd0.75F4 were prepared and the wavelength, temperature, and magnetic field dependence of the Faraday rotation measured. Optical‐absorption spectra and refractive indices are also reported. The Faraday effect in these materials is described by a paramagnetic rotation with the primary oscillator strength arising from 4f8→4f75d electronic transitions of the Tb3+ ions. Whereas LiTbF4 orders ferromagnetically at low temperatures, the mixed crystals exhibited no ordering at T?1.25 K. Low‐temperature Faraday rotation measurements of KTb3F10 do not indicate ferromagnetic order above 1.66 K. KTb3F10 and LiTbF4 crystals have large Verdet constants, are transparent in the visible and near infrared and have small nonlinear refractive‐index coefficients. These materials are therefore useful for optical rotators and in high‐power laser applications.

Magneto‐optical properties of KTb3F10 and LiTbF4 crystals

Optical and magnetic properties of Er3+ in LiYF4

The flux growth of the following complex fluorides is reported: KNiCrF6; RbCoCrF6, RbMnCrF6; CsCoAIF6, CsCoCrF6, CsCoFeF6; CsCrAIF6; CsMgAIF6, CsMgCrF6, CsMgFeF6; CsMnAIF6, CsMnCrF6, CsMnFeF6; CsNiAIF6, CsNiCrF6, CsNiFeF6; CsZnFeF6. Octahedral crystals of some of these materials with edges up to 1 cm have been grown. Most of them are cubic, but several are twinned, indicating a structural phase transition below the growth temperature. The growth of KCr2 F6.5 and BaNiF3.6Cl0.4 crystals is also described. Larger faceted crystals of K2FeF5 are reported. The growth of crystals of KFe2F6, previously only prepared under HF and N2, has been achieved in air.

T. Johansson

Papers

Ferromagnetism in LiTbF4