JETP Letters: issues online

The behavior in magnetic fields of a highly correlated electron liquid approaching the fermion condensation quantum phase transition from the disordered phase is considered. We show that at sufficiently high temperatures $T\geq T^*(x)$ the effective mass starts to depend on T, $M^*\propto T^{-1/2}$ . This T^-1/2 dependence of the effective mass at elevated temperatures leads to the non-Fermi liquid behavior of the resistivity, $\rho(T)\propto T$ and at higher temperatures $\rho(T)\propto T^{3/2}$ . The application of a magnetic field B restores the common T² behavior of the resistivity. The effective mass depends on the magnetic field, $M^*(B)\propto B^{-2/3}$ , being approximately independent of the temperature at $T\leq T^*(B)\propto B^{4/3}$ . At $T\geq T^*(B)$ , the T^-1/2 dependence of the effective mass is re-established. We demonstrate that this B-T phase diagram has a strong impact on the magnetoresistance (MR) of the highly correlated electron liquid. The MR as a function of the temperature exhibits a transition from the negative values of MR at T→ 0 to the positive values at $T\propto B^{4/3}$ . Thus, at $T\geq T^*(B)$ , MR as a function of the temperature possesses a node at $T\propto B^{4/3}$ .