The low-temperature decimeter wave impedance of aluminium measurements in transverse magnetic field

Abstract

The real part of low-temperature surface impedance of aluminium in magnetic field up to 7 T has been studied by the method of registration of the own Q-factor of coaxial shortinged cylindrical resonator, being constructed entirely from the examined material. The wavelength of radio frequence (RF) field was equal to 70 cm. All measurements were made in a helium cryostat with superconducting magnet. The studied resonator was placed in a cylindrical thermostat and oriented parallel to the magnetic field. The magnetic field dependence of the impedance was found to be different at the helium, hydrogen and nitrogen temperatures. So at T = 4.2–30 К the impedance is nonmonotonic function of magnetic field and at higher temperatures the surface impedance has monotonic increase with magnetic field. This behaviour deals with the shortinged side of resonator oriented perpendicular to the external magnetic field, because of the fact that on the cylindrical surfaces of the resonator the RF current is collinear to the magnetic field and isn’t affected by it. At the low temperature and under the conditions of anomalous skin-effect the renormalising of the guantity of electrons is affected by both high and weak magnetic fields. At the higher temperature the skin – effect is close to normal and high frequency conductivity is monotonic function of the magnetic field.