Resistivity minima in concentrated gamma -Cu100-xMnx alloys (36

Abstract

High-resolution electrical resistivity data of concentrated \ensuremath{\gamma}-${\mathrm{Cu}}_{100\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$ alloys with x=36, 60, 73, 76, and 83 have been presented here in the temperature range 1.2\ensuremath{\le}T\ensuremath{\le}30 K. They show resistivity minima at ${\mathit{T}}_{\mathrm{min}}$ lying between 2.5 and 24.5 K. In this temperature range the alloys with x=36, 60, and 73 are cluster glasses while those with x=76 and 83 show a mixed cluster-glass and long-range antiferromagnetic phase. Resistivity below the minima follows a \ensuremath{\surd}T type of behavior and has been interpreted in terms of the electron-electron (e-e) interaction effects in the presence of weak localization. The e-e interaction effects have dominant contributions to the resistivity in the temperature range of 2 K\ensuremath{\le}T\ensuremath{\le}${\mathit{T}}_{\mathrm{min}}$/3. The contributions from magnetic and phonon scattering are found to be negligible in this range. A good estimation of the density of states at the Fermi level, made from the coefficient of the \ensuremath{\surd}T term, gives further support to the interpretation. In the higher temperature range of ${\mathit{T}}_{\mathrm{min}}$/3\ensuremath{\le}T\ensuremath{\le}30 K, besides the e-e interaction effects, magnetic contribution of the type ${\mathit{T}}^{3/2}$ and phonon contribution given by the standard Bloch-Gr\uneissen relation have been observed. From our present findings and the earlier reports on other systems, we conclude that the ${\mathit{T}}^{3/2}$ type of magnetic contribution to the resistivity arises due to the low-temperature spin diffusive modes in spin/cluster glasses. The above analysis is insensitive to the magnetic state of the alloys. \textcopyright{} 1996 The American Physical Society.