{"id":1616,"date":"2025-12-02T17:56:59","date_gmt":"2025-12-02T08:56:59","guid":{"rendered":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/?post_type=topics&#038;p=1616"},"modified":"2025-12-02T17:57:16","modified_gmt":"2025-12-02T08:57:16","slug":"1616","status":"publish","type":"topics","link":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/topics\/1616\/","title":{"rendered":"Anisotropic exchange interactions in the ferromagnetic quantum critical material CeRh<sub>6<\/sub>Ge<sub>4<\/sub>"},"content":{"rendered":"<p>The 4f-electron compound CeRh<sub>6<\/sub>Ge<sub>4<\/sub> exhibits ferromagnetism at low temperatures. By applying the external pressure, the ferromagnetic transition temperature decreases toward absolute zero, showing a \u201cquantum critical phenomenon.\u201d A quantum critical phenomenon refers to a regime where quantum fluctuations strongly influence the physical properties. However, observing such behavior in a ferromagnet is considered unusual, because in most cases applying pressure enhances quantum fluctuations to destroy ferromagnetism. The question is why CeRh<sub>6<\/sub>Ge<sub>4<\/sub> can exhibit a quantum critical phenomenon.<\/p>\n<p>We investigated ferromagnetic fluctuations in CeRh<sub>6<\/sub>Ge<sub>4<\/sub> using dynamical mean-field theory (DMFT). As a result, we successfully reproduced the ferromagnetism by localized 4f electrons. Furthermore, we found that the interactions between 4f electrons that drive ferromagnetism possess strong anisotropy. When spin interactions are anisotropic, it is known that ferromagnetism can remain robust even under strong quantum fluctuations. Thus, we concluded that this anisotropic interaction stabilizes ferromagnetism and consequently allows the material to realize a quantum critical phenomenon in CeRh<sub>6<\/sub>Ge<sub>4<\/sub>.<\/p>\n<p>S. Itokazu, A. Kirikoshi, H. O. Jeschke, J. Otsuki<br \/>\n       <a href=\"https:\/\/www.nature.com\/articles\/s43246-025-00998-7\" rel=\"noopener\" target=\"_blank\"> Comm. Mater.  <strong>  6<\/strong>, 269 (2025)\uff0dPublished 25 November, 2025<\/a><\/p>\n<p><img decoding=\"async\" src=\"http:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2025\/12\/CeRh6Ge4_wide-1024x522.png\" alt=\"\" width=\"800\" class=\"aligncenter size-large wp-image-1603\" srcset=\"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2025\/12\/CeRh6Ge4_wide-1024x522.png 1024w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2025\/12\/CeRh6Ge4_wide-300x153.png 300w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2025\/12\/CeRh6Ge4_wide-768x392.png 768w, https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-content\/uploads\/2025\/12\/CeRh6Ge4_wide.png 1200w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The 4f-electron compound CeRh6Ge4 exhibits ferromagnetism at low temperatures. B &#8230; <\/p>\n","protected":false},"author":1,"featured_media":1602,"menu_order":0,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-1616","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\/1616","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\/1616\/revisions"}],"predecessor-version":[{"id":1620,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/topics\/1616\/revisions\/1620"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/media\/1602"}],"wp:attachment":[{"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/media?parent=1616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/categories?post=1616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.physics.okayama-u.ac.jp\/jeschke-otsuki-group\/wp-json\/wp\/v2\/tags?post=1616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}