In the mid-1990's a class of magnetic oxide materials (A1-xBxMnO3: A = rare earth, B = alkaline earth) was found to exhibit a very large change in electrical resistance upon application of an external magnetic field. This so-called colossal magnetoresistance (CMR) effect has led to an intense, worldwide research effort in recent years to understand the basic physics of these materials and to explore potential applications of these materials as magnetic sensors. The CSR has an acitve research program in this area, primarly in conjunction with the Maryland NSF MRSEC.

Beside the CMR, the manganite materials exhibit other remarkable electronic properties. An interplay among the charge carriers, magnetic coupling, orbital ordering and structural distortion, leads to a variety of physical properties, ranging from ferromagnetic (FM) metal to antiferromagnetic (AFM) charge-ordered (CO) insulator depending on the concentration of dopant (x), temperature, and magnetic field. A detailed understanding in the manganites of such phenomena as the metal-insulator transition with composition and temperature variation, the CMR effect, the ``melting'' of the charge ordering in a modest magnetic field and the electronic phase separation is presently lacking. Our research is carried out in order to better understand some of these novel phenomena. To study these exciting materials we use different techniques such as: low temperature relaxation calorimetry, SQUID magnetometry, low temperature transport measurements in magnetic field, STM, AFM, neutron and electron scattering.

Our research is focused in the following areas:

1. Strain Effects (Greene, Venky)
2. Electroresistance and electronic phase separation in mixed-valent manganites. (Venky)
3. Probing the Magnetism and chemistry of a burried oxide layer. (Venky
 

Center for Superconductivity Research, University of Maryland, College Park, MD 20742-4111
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