Electronic properties of hydrogen-doped (Zr_80 3d_20)_1-xH_x (3d = Fe, Co, Ni) metallic glasses

The electrical resistivities of hydrogen-doped (Zr_80 3d_20)_1-xH_x (3d = Fe, Co, Ni; x ≤ 0.11) metallic glasses have been measured at temperatures between 2 K and 290 K. The increase of the room-temperature resistivity and its temperature coefficient are explained as a consequence of increased disorder due to hydrogen-doping. The temperature dependence of the resistivity has been analysed using theoretical models of weak-localisation and electron-electron interaction in disordered three-dimensional conductors. The hydrogen dopant is found to reduce effective electron diffusion constant, D, the spin-orbit scattering rate, τ_so^-1, the superconducting transition temperature, T_c, and broadens the superconducting transition region. We discuss the effects of different hydrogen environments on T_c of (Zr_80 3d_20)_1-xH_x metallic glasses

Elekronska svojstva hidrogeniziranih metalnih stakala (Zr803d20)1−xHx (3d = Fe, Co, Ni)

The electrical resistivities of hydrogen-doped (Zr803d20)1-xHx (3d = Fe, Co, Ni; x Ł 0.11) metallic glasses have been measured at temperatures between 2 K and 290 K. The increase of the room-temperature resistivity and its temperature coefficient are explained as a consequence of increased disorder due to hydrogen-doping. The temperature dependence of the resistivity has been analysed using theoretical models of weak-localisation and electron-electron interaction in disordered three-dimensional conductors. The hydrogen dopant is found to reduce effective electron diffusion constant, D, the spin-orbit scattering rate, τ so-1, the superconducting transition temperature, Tc, and broadens the superconducting transition region. We discuss the effects of different hydrogen environments on Tc of (Zr803d20)1-xHx metallic glasses.Mjerili smo električnu otpornost hidrogeniziranih metalnih stakala (Zr803d20)1−xHx (3d = Fe, Co, Ni; x ≤ 0.11) na temperaturama između 2 K i 290 K. Porast otpornosti na sobnoj temperaturi i njen temperaturni koeficijent tumače se kao posljedica povećanog nereda zbog dodavanja vodikovih atoma. Temperaturna ovisnost otpornosti se analizira primjenom teorijskih modela slabe lokalizacije i interakcije medu elektronima u neuređenim trodimenzijskim vodičima. Našli smo da hidrogenizacija smanjuje konstantu djelotvorne elektronske difuzije, D, učestalost raspršenja spin-staza, τ −1 so , temperaturu supravodljivog prijelaza, Tc, i širi područje supravodljivog prijelaza. Raspravljamo o učinku različitih vodikovih okolina na Tc u metalnim staklima (Zr803d20)1−xHx

Elekronska svojstva hidrogeniziranih metalnih stakala (Zr803d20)1−xHx (3d = Fe, Co, Ni)

The electrical resistivities of hydrogen-doped (Zr803d20)1-xHx (3d = Fe, Co, Ni; x Ł 0.11) metallic glasses have been measured at temperatures between 2 K and 290 K. The increase of the room-temperature resistivity and its temperature coefficient are explained as a consequence of increased disorder due to hydrogen-doping. The temperature dependence of the resistivity has been analysed using theoretical models of weak-localisation and electron-electron interaction in disordered three-dimensional conductors. The hydrogen dopant is found to reduce effective electron diffusion constant, D, the spin-orbit scattering rate, τ so-1, the superconducting transition temperature, Tc, and broadens the superconducting transition region. We discuss the effects of different hydrogen environments on Tc of (Zr803d20)1-xHx metallic glasses.Mjerili smo električnu otpornost hidrogeniziranih metalnih stakala (Zr803d20)1−xHx (3d = Fe, Co, Ni; x ≤ 0.11) na temperaturama između 2 K i 290 K. Porast otpornosti na sobnoj temperaturi i njen temperaturni koeficijent tumače se kao posljedica povećanog nereda zbog dodavanja vodikovih atoma. Temperaturna ovisnost otpornosti se analizira primjenom teorijskih modela slabe lokalizacije i interakcije medu elektronima u neuređenim trodimenzijskim vodičima. Našli smo da hidrogenizacija smanjuje konstantu djelotvorne elektronske difuzije, D, učestalost raspršenja spin-staza, τ −1 so , temperaturu supravodljivog prijelaza, Tc, i širi područje supravodljivog prijelaza. Raspravljamo o učinku različitih vodikovih okolina na Tc u metalnim staklima (Zr803d20)1−xHx

Influence of hydrogen on the superconducting and the paramagnetic properties of some Zr-3d metallic glasses

We present the experimental results on the effects of hydrogen doping on the superconducting and paramagnetic properties of zirconium-rich (x > 0.66) Zr_x3d_1-x metallic glasses. Zr_0.70Cu_0.30, Zr_0.67Ni_0.33 and Zr_0.67Co_0.33 are superconductors with a superconducting transition temperature in the vicinity of 2 K, while Zr_0.68Fe_0.32 is a paramagnet down to very low temperatures because of pronounced spin-fluctuations. The magnetoresistivity data are analysed using theoretical models of weak location and electron-electron interactions. Doping with hydrogen reduces the superconducting transition temperature in Zr_0.70Cu_0.30, Zr_0.67Ni_0.33 and Zr_0.67Co_0.33 metallic glasses. The magnetoresistivity enhancement of hydrogen-doped Zr_0.68Fe_0.32 has been attributed to the increase of the Stoner factor, (1-I)^-1. That increase indicates an enhancement of spin fluctuations with hydrogen

Upotreba vodika kao probe za proučavanje kvantne interferencije na defektima u metalnim staklima

The electrical resistivity and the magnetic susceptibility of hydrogen-doped disordered Zr-Ni alloys have been measured at temperatures between 1.7 K and 300 K and in magnetic fields up to 6 T for various dopant concentrations. The temperature and magnetic field dependence of the measured properties have been analysed using the theoretical models of weak-localization and electron-electron interaction in disordered three-dimensional conductors. Doping the samples with hydrogen increases the disorder. Thus, we have found that hydrogen strongly enhances quantum interference at deffects. As a result the effective diffusion constant of the electrons and the screening of the Coulomb interaction are reduced. This leads to an increase in resistivity, suppression of the superconducting transition temperature, and to enhanced spin susceptibility at low temperatures. The Maki-Thompson interaction as well as the spin-orbit contribution to the magnetoresistivity are also depressed.Prikazani su rezultati mjerenja električne otpornosti i magnetske susceptibilnosti (Zr-Ni)-H ultrabrzo kaljenih metalnih stakala u temperaturnom intervalu od 1.7 K do 300 K te u magnetskim poljima do 6 T u ovisnosti o koncentraciji absorbiranog vodika. Anomalna ovisnost mjerenih svojstava o temperaturi i magnetskom polju interpretirana je u svjetlu novijih teorijskih modela slabe lokalizacije i elektronelektron interakcije u neured–enim trodimenzionalnim vodičima. Dopiranje vodikom povećava nered u sistemu, a time i kvantnu interferenciju na defektima. Kao rezultat toga dolazi do smanjenja difuzione konstante elektrona i smanjenja zasjenjenja efektivne Coulombove interakcije. Ovo dovodi do opaženog povećanja otpornosti, smanjenja temperature supervodljivog prijelaza te povećanja magnetske susceptibilnosti na niskim temperaturama. Također su smanjeni doprinosi spin-orbitalnog raspršenja i Maki-Thompsonove interakcije magnetootpornosti

Hydrogen-induced degradation of T_c in Zr-Ni and Zr-Cu metallic glasses

We have studied the effect of hydrogen doping of Zr-3d metallic glasses on the superconducting transition temperature T_c. It is shown that the degradation of T_c is well accounted for by Anderson localization in highly disordered systems

Magnetic susceptibility of Zr_80Co_20)_1-xH_x metalic glasses

The magnetisation of hydrogen-doped (Zr_80Co_20)_1-xH_x metallic glasses has been measured in the temperature range 1.7 K -100 K for various dopant concentrations. The system is paramagnetic and becomes superconducting at T_c = 3.98 K. The magnetic susceptibility of the undoped sample above Tc is strongly temperature dependent and shows the Curie-Weiss behaviour, whereas in the doped amples it is temperature independent. It has been also found that the magnetic susceptibility at 100 K, χ(100 K), decreases with hydrogen concentration. The low-temperature upturn in the undoped sample most likely results from a small amount of magnetic impurities. Doping the sample with small hydrogen concentration results in the screening of magnetic impurities thus reducing the Curie-Weiss contribution to the magnetic susceptibility. The form and magnitude of the observed temperature dependence of the magnetic susceptibility are well accounted for by the sum of the Curie-Weiss term and the quantum corrections to the susceptibility

Weak-localization and Coulomb-interaction effects in hydrogen-doped Zr-Ni and Zr-Cu metallic glasses

Measurements are described and the results presented for the temperature and magnetic field dependence of the electrical conductivity and for the magnetic susceptibility of Zr-Ni and Zr-Cu metallic glasses doped with hydrogen. Hydrogen is found to reduce both the effective electron diffusion constant and the screening of the Coulomb interaction which leads to a decrease in the conductivity, suppression of the superconducting transition temperature, and to an enhancement of the spin susceptibility at low temperatures. The relative contributions of the spin-orbit and the Maki-Thompson interaction to the magnetoresistivity are also depressed. It is shown that the theoretical models of weak localization and Coulomb interaction provide both a good qualitative and quantitative description of the anomalous temperature and field dependence of the measured properties

Superconducting properties of thermally-relaxed Zr_80Co_20 metallic glass.

We have studied the effect of thermal relaxation on the superconducting properties of Zr_80Co_20 metallic glass by means of differential scanning calorimetry and electrical resistivity measurements in the vicinity of the superconducting transition temperature T_c. Experimental values for the crystallisation temperature and activation energy of the crystallisation processes were derived by studying these processes at different heating rates. The T_c of the Zr_80Co_20 metallic glass thermally relaxed with a heating rate of 60 K/min to slightly below its first crystallisation exotherm is higher than in unrelaxed Zr_80Co_20 metallic glass, whereas in all other thermally relaxed samples Tc decreases with decreasing heating rates and increasing temperature of relaxation. The homogeneity of the thermally relaxed Zr_80Co_20 metallic glass is discussed by using the superconducting transition width as a criterion. The superconducting transitions of thermally relaxed Zr_80Co_20 metallic glass samples are characterised by a sharp fall in electrical resistance. This suggests that the samples are homogeneous on a spatial scale of less than the zero-temperature coherence length ζ0

Utjecaj vodika na supravodljiva i paramagnetska svojstva nekih Zr-3d metalnih stakala

We present the experimental results on the effects of hydrogen doping on the superconducting and paramagnetic properties of zirconium-rich (x > 0.66) Zrx3d1-x metallic glasses. Zr0.70Cu0.30, Zr0.67Ni0.33 and Zr0.67Co0.33 are superconductors with a superconducting transition temperature in the vicinity of 2 K, while Zr0.68Fe0.32 is a paramagnet down to very low temperatures because of pronounced spin-fluctuations. The magnetoresistivity data are analysed using theoretical models of weak location and electron-electron interactions. Doping with hydrogen reduces the superconducting transition temperature in Zr0.70Cu0.30, Zr0.67Ni0.33 and Zr0.67Co0.33 metallic glasses. The magnetoresistivity enhancement of hydrogen-doped Zr0.68Fe0.32 has been attributed to the increase of the Stoner factor, (1-I)-1. That increase indicates an enhancement of spin fluctuations with hydrogen.Prikazuju se eksperimentalni rezultati utjecaja vodika na supravodljiva i paramagnetska svojstva Zrx3d1−x metalnih stakala bogatih cirkonijem (x > 0.66). Zr0.70Cu0.30, Zr0.67Ni0.33 i Zr0.67Co0.33 su supravodiči s temperaturom supravodljivog prijelaza oko 2 K, dok je Zr0.68Fe0.32 paramagnetičan i na veoma niskim temperaturama zbog prisustva spinskih fluktuacija. Rezultati magnetootpora analizirani su primjenom teorijskih modela slabe lokalizacije i elektron-elektron interakcije u neuređenim sistemima. Dopiranje vodikom dovodi do sniženja temperature supravodljivog prijelaza u Zr070Cu0.30, Zr0.67Ni0.33 i Zr0.67Co0.33 metalnim staklima. Povećanje magnetootpora u Zr0.68Fe0.32 dopiranim vodikom uzrokovano je povećanjem Stonerovog faktora. Ovo povećanje ukazuje na povećanje spinskih fluktuacija pod utjecajem vodika