{"id":1813,"date":"2026-05-15T13:54:33","date_gmt":"2026-05-15T04:54:33","guid":{"rendered":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/?post_type=topics&#038;p=1813"},"modified":"2026-05-15T13:54:33","modified_gmt":"2026-05-15T04:54:33","slug":"a-first-principles-approach-to-identifying-nontrivial-order-in-the-rare-earth-compound-cerh2as2","status":"publish","type":"topics","link":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/topics\/a-first-principles-approach-to-identifying-nontrivial-order-in-the-rare-earth-compound-cerh2as2\/","title":{"rendered":"A first-principles approach to identifying nontrivial order in the rare-earth compound CeRh<sub>2<\/sub>As<sub>2<\/sub>"},"content":{"rendered":"<p>A rare-earth compound discovered in 2021, <\/p>\n<p>CeRh<sub>2<\/sub>As<sub>2<\/sub>, is known as a \u201cmultiphase superconductor\u201d that exhibits multiple superconducting states under magnetic fields. In addition, it displays a rich variety of physical properties in which multiple orders coexist and compete, including the coexistence of superconductivity and antiferromagnetism, as well as the emergence of a nontrivial ordered phase (called Phase I) above the superconducting transition temperature. While conventional antiferromagnetic order is generally suppressed and destroyed by external magnetic fields, Phase I of CeRh<sub>2<\/sub>As<sub>2<\/sub> exhibits a characteristic anisotropy in which the order is enhanced only under in-plane magnetic fields. At present, active debate continues regarding whether the origin of Phase I  is magnetic order or electric quadrupole order, as well as its relationship to multiphase superconductivity and antiferromagnetism.<\/p>\n<p>To identify the order parameter of Phase I in CeRh<sub>2<\/sub>As<sub>2<\/sub>, we performed first-principles calculations of quantities known as \u201cmultipole fluctuations\u201d using the DFT+DMFT method, which combines density functional theory (DFT) with dynamical mean-field theory (DMFT). Our calculations revealed the development of antiferromagnetic fluctuations and clarified that Phase I corresponds to a two-dimensional antiferromagnetic order characterized by magnetic moments aligned along the c-axis. Furthermore, we demonstrated that the enhancement of the order under in-plane magnetic fields can be explained by contributions from field-induced electric quadrupoles.<\/p>\n<p>This study represents one of the few successful examples in which a first-principles approach has been applied not only to reproduce known ordered states but also to elucidate nontrivial hidden ordered states in rare-earth compounds. The fact that the proposed ordered state is consistent with experimental observations demonstrates that this method is a powerful approach for uncovering unknown properties of strongly correlated materials.<\/p>\n<p>K. Numa, E. Matsuda, A. Kirikoshi, J. Otsuki<br \/>\n       <a href=\"https:\/\/doi.org\/10.1103\/nw88-plgx\" rel=\"noopener\" target=\"_blank\"> Phys. Rev. B<strong> 113<\/strong>, 115141 (2026) \u2013 Published 18 March, 2026<\/a><\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2026\/05\/HP_fig-1-1024x530.png\" alt=\"\" width=\"800\" class=\"aligncenter size-large wp-image-1805\" srcset=\"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2026\/05\/HP_fig-1-1024x530.png 1024w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2026\/05\/HP_fig-1-300x155.png 300w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2026\/05\/HP_fig-1-768x397.png 768w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2026\/05\/HP_fig-1-1536x794.png 1536w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2026\/05\/HP_fig-1-2048x1059.png 2048w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A rare-earth compound discovered in 2021, CeRh2As2, is known as a \u201cmultiphase su &#8230; <\/p>\n","protected":false},"author":1,"featured_media":1811,"menu_order":0,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-1813","topics","type-topics","status-publish","format-standard","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/topics\/1813","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/types\/topics"}],"author":[{"embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":4,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/topics\/1813\/revisions"}],"predecessor-version":[{"id":1817,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/topics\/1813\/revisions\/1817"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/media\/1811"}],"wp:attachment":[{"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/media?parent=1813"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/categories?post=1813"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/tags?post=1813"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}