{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T02:04:33Z","timestamp":1774922673028,"version":"3.50.1"},"reference-count":20,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2023,4,26]],"date-time":"2023-04-26T00:00:00Z","timestamp":1682467200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institute of Materials Physics","award":["PC2-PN23080202"],"award-info":[{"award-number":["PC2-PN23080202"]}]},{"name":"National Institute of Materials Physics","award":["CA19108 Hi-SCALE"],"award-info":[{"award-number":["CA19108 Hi-SCALE"]}]},{"name":"National Institute of Materials Physics","award":["CA20116 OPERA"],"award-info":[{"award-number":["CA20116 OPERA"]}]},{"name":"National Institute of Materials Physics","award":["CA21144 SUPERQUMAP"],"award-info":[{"award-number":["CA21144 SUPERQUMAP"]}]},{"name":"EU COST Actions","award":["PC2-PN23080202"],"award-info":[{"award-number":["PC2-PN23080202"]}]},{"name":"EU COST Actions","award":["CA19108 Hi-SCALE"],"award-info":[{"award-number":["CA19108 Hi-SCALE"]}]},{"name":"EU COST Actions","award":["CA20116 OPERA"],"award-info":[{"award-number":["CA20116 OPERA"]}]},{"name":"EU COST Actions","award":["CA21144 SUPERQUMAP"],"award-info":[{"award-number":["CA21144 SUPERQUMAP"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>For practical applications of superconductors, understanding the vortex matter and dynamics is of paramount importance. An important issue in this context is the transition of the vortex glass, which is a true superconducting phase, into a vortex liquid phase having a linear dissipation. By using multi-harmonic susceptibility studies, we have investigated the vortex glass\u2014vortex liquid phase transitions in CaKFe4As4 and BaFe2(As0.68P0.32)2 single crystals. The principle of our method relates the on-set of the third-harmonic susceptibility response with the appearance of a vortex-glass phase in which the dissipation is non-linear. Similar to the high-critical temperature cuprate superconductors, we have shown that even in these iron-based superconductors with significant lower critical temperatures, such phase transition can be treated as a melting in the sense of Lindemann\u2019s approach, considering an anisotropic Ginzburg-Landau model. The experimental data are consistent with a temperature-dependent London penetration depth given by a 3D XY fluctuations model. The fitting parameters allowed us to extrapolate the vortex melting lines down to the temperature of liquid hydrogen, and such extrapolation showed that CaKFe4As4 is a very promising superconducting material for high field applications in liquid hydrogen, with a melting field at 20 K of the order of 100 T.<\/jats:p>","DOI":"10.3390\/ijms24097896","type":"journal-article","created":{"date-parts":[[2023,4,27]],"date-time":"2023-04-27T02:50:00Z","timestamp":1682563800000},"page":"7896","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Vortex Glass\u2014Vortex Liquid Transition in BaFe2(As1-xPx)2 and CaKFe4As4 Superconductors from Multi-Harmonic AC Magnetic Susceptibility Studies"],"prefix":"10.3390","volume":"24","author":[{"given":"Ion","family":"Ivan","sequence":"first","affiliation":[{"name":"National Institute of Materials Physics, 405A Atomistilor Str., 077125 Magurele, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alina M.","family":"Ionescu","sequence":"additional","affiliation":[{"name":"National Institute of Materials Physics, 405A Atomistilor Str., 077125 Magurele, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6938-3765","authenticated-orcid":false,"given":"Daniel N.","family":"Crisan","sequence":"additional","affiliation":[{"name":"National Institute of Materials Physics, 405A Atomistilor Str., 077125 Magurele, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0662-0177","authenticated-orcid":false,"given":"Adrian","family":"Crisan","sequence":"additional","affiliation":[{"name":"National Institute of Materials Physics, 405A Atomistilor Str., 077125 Magurele, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1007\/BF00117160","article-title":"Pinning in Type II Superconductors","volume":"34","author":"Larkin","year":"1979","journal-title":"J. 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