On estimating superconducting shielding volume fraction from susceptibility in pressurized Ruddlesden-Popper nickelates: Response to arXiv:2602.19282

TL;DR

This paper defends the standard method for estimating superconducting shielding volume fraction from susceptibility measurements, clarifying misconceptions and highlighting the importance of considering demagnetization effects in finite samples.

Contribution

It clarifies that the established methodology for evaluating shielding volume fraction is valid and widely used, countering recent claims of novelty and proposing an accurate interpretation for finite, demagnetized samples.

Findings

The standard evaluation method is based on the magnetostatic self-consistency relation.

The discrepancies in the recent preprint are due to a flawed assumption about linear proportionality.

Proper consideration of demagnetization effects is crucial for accurate susceptibility analysis.

Abstract

In a recent preprint (arXiv:2602.19282) [1], the authors questioned the procedure we used to evaluate the demagnetization-corrected superconducting shielding volume fraction in pressurized Ruddlesden-Popper nickelates [2-5]. They further claimed that this methodology has neither been derived nor used previously, and they proposed an alternative normalization scheme. Here we clarify that our evaluation follows directly from the standard magnetostatic self-consistency relation for finite samples and has been widely adopted in the superconductivity literature for decades. We also demonstrate that the discrepancies claimed in Ref. [1] stem from a fundamental flaw in their approach, namely, the assumption that the measured diamagnetic moment is linearly proportional to the superconducting shielding volume fraction in the presence of a finite demagnetization factor N. This assumption is not valid for strongly demagnetized, thin disk-like specimens, where the internal field and the measured moment are coupled self-consistently through the demagnetizing field.