The measurements of intensity of ultrasonic resonances below the transition to the superconducting state in a tetragonal metal cannot distinguish between the magnetic and nonmagnetic superconducting states with two-component order parameters.
@article{arxiv.2009.03263,
title = {Magnetic versus nonmagnetic superconducting states in Sr$_2$RuO$_4$},
author = {V. P. Mineev},
journal= {arXiv preprint arXiv:2009.03263},
year = {2020}
}
Comments
1 page The piezo-magnetic term Eq.(4) is not invariant in respect of group D_4(E) Eq.(3). So, piezo-magnetic energy does not exist and play no role in the interpretation of ultrasound experiments