Magnetotransport in nearly antiferromagnetic metals

We present a theory of the magnetotransport in weakly disordered metals clo se to an antiferromagnetic quantum-critical point, The anisotropic scatteri ng from critical spin fluctuations is strongly influenced by weak but isotr opic scattering from small amounts of disorder. This leads to a large regim e where the resistivity obeys a scaling form rho= rho(0) + Delta rho approx imate to rho(0) + T(3/2)f[T/rho(0),(p -p(c))/rho(0),B/rho(0)(3/2)], where r ho(0) is the residual resistivity, B the magnetic field, and p-p(c)>0 measu res the distance from the quantum-critical point on the paramagnetic side o f the phase diagram. Orbital effects of the magnetic field are most pronoun ced in very clean samples for not too low temperatures, where the resistivi ty for increasing magnetic field crosses over from a linear temperature dep endence Delta p similar to T root rho(0) to a resistivity linear in B and i ndependent of T and rho(0). At higher magnetic fields, Delta rho saturates at a value proportional to T-1.5 or T-2/(p-p(c)). Deviations from scaling, the interplay of orbital and spin contributions of the magnetic field, and experimental test of the spin-fluctuation model are discussed in detail.