Magnetically modulated microwave absorption in cuprate superconductors

Abstract

Abstraet. Magnetically modulated microwave absorption (MMMA) is a highly sensitive microprobe, which is increasingly being used to extract a variety of information about the flux dynamics in the high-transition-temperature superconductors. The correspondence between the information obtained from the MMMA and the directly monitored (without modulation) field-induced microwave absorption techniques is discussed. The validity of some of the commonly held views about the features that characterize the MMMA signal are examined.

Magnetic field modulated microwave spectroscopy across phase transitions and the search for new superconductors

“…Modulated microwave absorption on temperature sweep mode has been used to measure twin boundaries in high-T c superconductors [49,64], Bi 2 Sr 2 CaCu 2 O whiskers [65], powder and bulk MgB 2 [66,67], organic superconductors [68], and more recently, ternary borides Mo 2 Re 3 B and Mo 3 Re 2 B [69]. Correlation of the MFMMS signal with the dc magnetization [70] and comparison with the direct absorption technique (no modulation) was addressed for YBa 2 Cu 3 O 7−x [71,72]. Similar approaches have been used in other systems like PbBi 2 Sr 2 Ca 2 Cu 3 O y [8].…”

Al-doped MgB2 materials studied using electron paramagnetic resonance and Raman spectroscopy

“…28 However, it is not possible to determine quantitatively the dependency of the superconducting fraction from EPR. 39 Accordingly, at this point it is important to note that Kim et al 40 and Tyagi, Gould, and Bhagat et al [41][42][43] studied non-resonant magnetically modulated microwave absorption (MMMA) method below the critical transition temperature which has proved to be a useful method to probe the electrodynamic behavior of superconductors. Of course EPR is not a convenient technique to study the superconducting states in general.…”