ESR Spectrometry of High-Temperature Superconductors with Temperature-Modulation-Based Thermoregulation

A light-beam-assisted temperature-control system operating within a temperature range from 77 to 180 K is developed for investigating the absorption of electromagnetic waves by high-temperature superconductors in the vicinity of superconducting transition with an ESR spectrometer. The advantage of this system is the feasibility of modulating the temperature of a sample with a frequency of 80 Hz and amplitude of 10 ÷ 10K. The rms temperature instability over a 5-min time interval is within 0.06 K, the temperature gradient in a sample is ∼ 10K/mm for T ∼ 90K, and the system relaxation time is 1 – 10 s. The microwave absorption peaks in the vicinity of the superconducting transition of an Y Ba2Cu3O7−x, single crystal were first measured at (the simultaneous application of magnetic and temperature modulations.