A resistividade elétrica de ligas CoFe, onde a concen tração de ferro varia de 0 a 10 at%, foi medida no intervalo de temperatura entre 4°K e 300°K. Os resultados permitiram separar as ligas em diluídas e concentradas. Para as ligas diluídas interpretou-se os desvios da regra de Matthiessen em termos de um modelo de condução por duas bandas acopladas. Nas amostras concentradas, os efeitos de transições de fase estruturais tornam a resistividade elétrica em função complicada da temperatura e da concentração. / The electric resistivity measurements on CoFe alloys have been performed as a function of temperature in the interval 4 < T < 300°K, and iron concentration 0 < c < 10 at%. The deviations from Matthiessen's rule for up to 4 at% Fe was possible to interpret in terras of a coupled two band conduction model. The electric resistivity of the high iron concentration alloys (c > 4 at% Fe) has been proved to be an involved function of the temperature and concentration, due to phase transition effects.

Neste trabalho estudamos o problema da condução utilizando o modelo das duas correntes de elétrons de spins opostos, incluindo efeitos de espalhamento com inversão de spin. Em particular, discutimos teoricamente a contribuição de espalhamnetos elétron-magnon à parte da resistividade elétrica que depende da temperatura, em metais e ligas magnéticas, no limite de baixas temperaturas. / In this work we study the conductivity problem by spin up and spin down eléctron currents, taking spin-flip process into account. In particular we discuss theoretically the low temperature contribution to the temperature-dependent part of the electrical resistivity from electron-magnon scattering in magnetic metals and dilute alloys.

A resistividade elétrica de ligas CoFe, onde a concen tração de ferro varia de 0 a 10 at%, foi medida no intervalo de temperatura entre 4°K e 300°K. Os resultados permitiram separar as ligas em diluídas e concentradas. Para as ligas diluídas interpretou-se os desvios da regra de Matthiessen em termos de um modelo de condução por duas bandas acopladas. Nas amostras concentradas, os efeitos de transições de fase estruturais tornam a resistividade elétrica em função complicada da temperatura e da concentração. / The electric resistivity measurements on CoFe alloys have been performed as a function of temperature in the interval 4 < T < 300°K, and iron concentration 0 < c < 10 at%. The deviations from Matthiessen's rule for up to 4 at% Fe was possible to interpret in terras of a coupled two band conduction model. The electric resistivity of the high iron concentration alloys (c > 4 at% Fe) has been proved to be an involved function of the temperature and concentration, due to phase transition effects.

Neste trabalho estudamos o problema da condução utilizando o modelo das duas correntes de elétrons de spins opostos, incluindo efeitos de espalhamento com inversão de spin. Em particular, discutimos teoricamente a contribuição de espalhamnetos elétron-magnon à parte da resistividade elétrica que depende da temperatura, em metais e ligas magnéticas, no limite de baixas temperaturas. / In this work we study the conductivity problem by spin up and spin down eléctron currents, taking spin-flip process into account. In particular we discuss theoretically the low temperature contribution to the temperature-dependent part of the electrical resistivity from electron-magnon scattering in magnetic metals and dilute alloys.

A resistividade elétrica de ligas CoFe, onde a concen tração de ferro varia de 0 a 10 at%, foi medida no intervalo de temperatura entre 4°K e 300°K. Os resultados permitiram separar as ligas em diluídas e concentradas. Para as ligas diluídas interpretou-se os desvios da regra de Matthiessen em termos de um modelo de condução por duas bandas acopladas. Nas amostras concentradas, os efeitos de transições de fase estruturais tornam a resistividade elétrica em função complicada da temperatura e da concentração. / The electric resistivity measurements on CoFe alloys have been performed as a function of temperature in the interval 4 < T < 300°K, and iron concentration 0 < c < 10 at%. The deviations from Matthiessen's rule for up to 4 at% Fe was possible to interpret in terras of a coupled two band conduction model. The electric resistivity of the high iron concentration alloys (c > 4 at% Fe) has been proved to be an involved function of the temperature and concentration, due to phase transition effects.

Neste trabalho estudamos o problema da condução utilizando o modelo das duas correntes de elétrons de spins opostos, incluindo efeitos de espalhamento com inversão de spin. Em particular, discutimos teoricamente a contribuição de espalhamnetos elétron-magnon à parte da resistividade elétrica que depende da temperatura, em metais e ligas magnéticas, no limite de baixas temperaturas. / In this work we study the conductivity problem by spin up and spin down eléctron currents, taking spin-flip process into account. In particular we discuss theoretically the low temperature contribution to the temperature-dependent part of the electrical resistivity from electron-magnon scattering in magnetic metals and dilute alloys.

This thesis studies the magnetoelastic, transport and magnetic properties of single crystals of yttrium and scandium dopped with rare earth magnetic impurities. From our measurements of magnetostriction on dilute alloys we derive the magnetoelastic coefficients of the interaction between isolated ions and lattice strains. Our magnetoresistance measurements give the exchange and quadrupole coefficients of the interaction of isolated ions with the conduction electrons. The aim of our magnetic measurements is mainly to study the spin glass properties at low temperatures. The yttrium-rare earth and scandiumorare earth dilute alloys are interesting systems to probe the typical properties predicted by mean field theory for spin glasses with uniaxial crystal field.

This thesis studies the magnetoelastic, transport and magnetic properties of single crystals of yttrium and scandium dopped with rare earth magnetic impurities. From our measurements of magnetostriction on dilute alloys we derive the magnetoelastic coefficients of the interaction between isolated ions and lattice strains. Our magnetoresistance measurements give the exchange and quadrupole coefficients of the interaction of isolated ions with the conduction electrons. The aim of our magnetic measurements is mainly to study the spin glass properties at low temperatures. The yttrium-rare earth and scandiumorare earth dilute alloys are interesting systems to probe the typical properties predicted by mean field theory for spin glasses with uniaxial crystal field.

This thesis studies the magnetoelastic, transport and magnetic properties of single crystals of yttrium and scandium dopped with rare earth magnetic impurities. From our measurements of magnetostriction on dilute alloys we derive the magnetoelastic coefficients of the interaction between isolated ions and lattice strains. Our magnetoresistance measurements give the exchange and quadrupole coefficients of the interaction of isolated ions with the conduction electrons. The aim of our magnetic measurements is mainly to study the spin glass properties at low temperatures. The yttrium-rare earth and scandiumorare earth dilute alloys are interesting systems to probe the typical properties predicted by mean field theory for spin glasses with uniaxial crystal field.