G. T. Woods

Long-range ferromagnetism and giant magnetocaloric effect in type VIII Eu8Ga16Ge30 clathrates

Long-range ferromagnetism and low-field giant magnetocaloric effect are observed in Eu8Ga16Ge30 with the type VIII clathrate crystal structure, a material that is better known for its thermoelectric properties. Magnetization and modified Arrott plots indicate that the system undergoes a second-order ferromagnetic-paramagnetic phase transition at ∼13K. The low-field giant magnetic entropy change (−ΔSM∼11.4J∕kgK for Δμ0H=3T) coupled with the absence of thermal hysteresis and field hysteresis makes the system very attractive for low temperature magnetic refrigeration. The giant magnetic entropy change originates from the large magnetization (7.97μB per Eu ion) and the sharp change with temperature at the paramagnetic-ferromagnetic transition.

Observation of charge ordering and the ferromagnetic phase transition in single crystal LSMO using rf transverse susceptibility

We performed temperature and field-dependent reversible transverse susceptibility (TS) measurements on a La0.85Sr0.15MnO3 single crystal at radio frequency (10MHz) using a resonant tunnel-diode oscillator technique. These dynamic experiments probe the coupled electronic, magnetic and structural transition in LSMO giving rise to the ferromagnetic transition and the charge-ordered phase. The effective magnetic anisotropy fields are directly probed across the entire range from the Curie temperature to lower temperatures well into the charge-ordered state. Overall, the TS experiments are demonstrated to be useful for studying magnetic anisotropy in the presence of structural and electronic transitions in these strongly coupled systems.

Magnetic and Electronic Properties of Eu 4 Sr 4 Ga 16 Ge 30

Magnetization, static and ac magnetic susceptibility, nuclear forward scattering, and electrical resistivity measurements have been performed on polycrystalline

Giant magnetocaloric effect in clathrates

{\mathrm{Eu}}_{4}{\mathrm{Sr}}_{4}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30}

Probing magnetic anisotropy and spin polarization in spintronic materials

, a type I clathrate that has divalent strontium and europium ions encapsulated within a

Spin polarization measurements on polycrystalline strontium ruthenates using point-contact Andreev reflection

\mathrm{Ga}\text{\ensuremath{-}}\mathrm{Ge}

Measurement of the transport spin polarization of doped strontium ruthenates using point contact Andreev reflection

framework. These data are compared with those of type I clathrates

Magnetic and electronic properties ofEu4Sr4Ga16Ge30

{\mathrm{Eu}}_{8}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30}

Magnetic transitions and giant magnetocaloric effect in Eu8Ga16Ge30 clathrates

and

Magnetic transitions and giant magnetocaloric effect in Eu

{\mathrm{Eu}}_{6}{\mathrm{Sr}}_{2}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30}