{"id":684,"date":"2012-06-27T12:56:54","date_gmt":"2012-06-27T12:56:54","guid":{"rendered":"http:\/\/blogs.kent.ac.uk\/strongcorrelations\/?p=684"},"modified":"2015-01-07T09:45:30","modified_gmt":"2015-01-07T09:45:30","slug":"684","status":"publish","type":"post","link":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/","title":{"rendered":"A new family of highly-exotic superconductors"},"content":{"rendered":"<ul class=\"kent-social-links\"><li><a href='http:\/\/www.facebook.com\/sharer.php?u=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/&amp;t=A new family of highly-exotic superconductors' target='_blank'><i class='ksocial-facebook' title='Share via Facebook'><\/i><\/a><\/li><li><a href='http:\/\/twitter.com\/home?status=A new family of highly-exotic superconductors%20https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/' target='_blank'><i class='ksocial-twitter' title='Share via Twitter'><\/i><\/a><\/li><li><a href='https:\/\/plus.google.com\/share?url=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/' target='_blank'><i class='ksocial-google-plus' title='Share via Google Plus'><\/i><\/a><\/li><li><a href='http:\/\/linkedin.com\/shareArticle?mini=true&amp;url=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/&amp;title=A new family of highly-exotic superconductors' target='_blank'><i class='ksocial-linkedin' title='Share via Linked In'><\/i><\/a><\/li><li><a href='mailto:content=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/&amp;title=A new family of highly-exotic superconductors' target='_blank'><i class='ksocial-email' title='Share via Email'><\/i><\/a><\/li><\/ul><figure id=\"attachment_685\" aria-describedby=\"caption-attachment-685\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"http:\/\/blogs.kent.ac.uk\/strongcorrelations\/files\/2012\/06\/Screenshot-1206.5905v1-1.pdf.png\"><img loading=\"lazy\" class=\"size-medium wp-image-685\" src=\"http:\/\/blogs.kent.ac.uk\/strongcorrelations\/files\/2012\/06\/Screenshot-1206.5905v1-1.pdf-300x93.png\" alt=\"Crystal structure diagram\" width=\"300\" height=\"93\" srcset=\"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/files\/2012\/06\/Screenshot-1206.5905v1-1.pdf-300x93.png 300w, https:\/\/blogs.kent.ac.uk\/strongcorrelations\/files\/2012\/06\/Screenshot-1206.5905v1-1.pdf-500x155.png 500w, https:\/\/blogs.kent.ac.uk\/strongcorrelations\/files\/2012\/06\/Screenshot-1206.5905v1-1.pdf.png 929w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-685\" class=\"wp-caption-text\">The crystal structure of LaNiGa2, a highly unconventional superconductor.<\/figcaption><\/figure>\n<p>We just got a paper accepted in Phys. Rev. Lett. where we report evidence of time-reversal symmetry breaking in LaNiGa2, which is chemically-speaking a close cousin of <a href=\"http:\/\/blogs.kent.ac.uk\/strongcorrelations\/?s=LaNiC2&amp;submit=Search\">LaNiC2<\/a>, though without the lack of inversion symmetry. We also offer a group-theoretical analysis of the pairing symmetry which, like in the case of LaNiC2, points to non-unitary triplet pairing. The paper also contains a bit of Ginzburg-Landau on which I comment some more below.<\/p>\n<p>This work suggests that LaNiC2 and LaNiGa2 are two members of a new family of very exotic superconductors. Until now, all known triplet superconductors were either unitary (i.e., with equal participation in pairing by spin-up and spin-down electrons) or non-unitary, but ferromagnetic. In the case of a ferromagnet non-unitary pairing (where spin-up and spin-down electrons participate in the pairing differently) can be simply explained by a pre-existing spin polarisation of the Fermi liquid before the onset of the superconducting instability. LaNiC2 and LaNiGa2 are paramagnets, which brings up the question how the non-unitary triplet pairing comes about. In the paper we offer a possible explanation: it turns out there is a generic term (required by symmetry) in the Ginzburg-Landau theory of any paramagnetic triplet superconductor that couples the non-unitary component of the order parameter to the magnetisation. In effect, if the pairing is non-unitary, it leads to a sub-dominant magnetisation, which in turn enhances the non-unitary triplet pairing. Thus non-unitary triplets can effectively lift themselves by their bootstraps through a mechanism that is the superocnducting analogue of the Stoner instability leading to ferromagnetism in some metals.<\/p>\n<p>The paper is in press, but we&#8217;ve just put it on the arXiv: A. D. Hillier, J. Quintanilla, B. Mazidian, J. F. Annett, R. Cywinski, <a href=\"http:\/\/arxiv.org\/abs\/1206.5905\">arxiv.org\/abs\/1206.5905.<\/a><\/p>\n<p><em>Note added.-<\/em> published reference: Hillier, A. D., Quintanilla, J., Mazidian, B., Annett, J. F. &amp; Cywinski, R. Nonunitary Triplet Pairing in the Centrosymmetric Superconductor LaNiGa<sub>2<\/sub>. <i>Physical Review Letters<\/i> <b>109,<\/b> (2012). <a href=\"http:\/\/dx.doi.org\/10.1103\/PhysRevLett.109.097001\">http:\/\/dx.doi.org\/10.1103\/PhysRevLett.109.097001<\/a><\/p>\n<ul class=\"kent-social-links\"><li><a href='http:\/\/www.facebook.com\/sharer.php?u=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/&amp;t=A new family of highly-exotic superconductors' target='_blank'><i class='ksocial-facebook' title='Share via Facebook'><\/i><\/a><\/li><li><a href='http:\/\/twitter.com\/home?status=A new family of highly-exotic superconductors%20https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/' target='_blank'><i class='ksocial-twitter' title='Share via Twitter'><\/i><\/a><\/li><li><a href='https:\/\/plus.google.com\/share?url=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/' target='_blank'><i class='ksocial-google-plus' title='Share via Google Plus'><\/i><\/a><\/li><li><a href='http:\/\/linkedin.com\/shareArticle?mini=true&amp;url=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/&amp;title=A new family of highly-exotic superconductors' target='_blank'><i class='ksocial-linkedin' title='Share via Linked In'><\/i><\/a><\/li><li><a href='mailto:content=https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/&amp;title=A new family of highly-exotic superconductors' target='_blank'><i class='ksocial-email' title='Share via Email'><\/i><\/a><\/li><\/ul>","protected":false},"excerpt":{"rendered":"<p>We just got a paper accepted in Phys. Rev. Lett. where we report evidence of time-reversal symmetry breaking in LaNiGa2, which is chemically-speaking a close &hellip; <a href=\"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/2012\/06\/27\/684\/\">Read&nbsp;more<\/a><\/p>\n","protected":false},"author":976,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[597],"tags":[],"_links":{"self":[{"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/posts\/684"}],"collection":[{"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/users\/976"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/comments?post=684"}],"version-history":[{"count":9,"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/posts\/684\/revisions"}],"predecessor-version":[{"id":1282,"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/posts\/684\/revisions\/1282"}],"wp:attachment":[{"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/media?parent=684"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/categories?post=684"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.kent.ac.uk\/strongcorrelations\/wp-json\/wp\/v2\/tags?post=684"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}