Mesoscopic fluctuations in colossal magnetoresistance

In the colossal magnetoresistive regime epitaxial single-crystal manganite samples exhibit discrete resistance fluctuations. Their overall dependence on magnetic field indicates fluctuations between states with different abso lute magnetization, not just different orientations. The dependences of Bol tzmann factors on field and temperature give the differences in magnetic mo ment and entropy between the states, and hence give the volumes of the fluc tuating domains. The large discrete resistance fluctuations imply strong in homogeneity of the current. Evidence for thermodynamic effects favoring a m ixed phase is given.