{"id":86757,"date":"2025-12-10T12:00:49","date_gmt":"2025-12-10T03:00:49","guid":{"rendered":"https:\/\/www.waseda.jp\/top\/en\/?p=86757"},"modified":"2025-12-07T16:32:40","modified_gmt":"2025-12-07T07:32:40","slug":"life-in-a-nutshell-new-species-found-in-the-carapace-of-late-cretaceous-marine-turtle-2-2-2-2-2-2-2-2-2-2-2-3-3-2-2-3-2-3-2-2-2-3-2-2-2-3-3-3-3-2-2-2-3-2-2-2-2-2-2-4-2-5-2-2-2","status":"publish","type":"post","link":"https:\/\/www.waseda.jp\/top\/en\/news\/86757","title":{"rendered":"Magnetic Ordering Induces Jahn\u2013Teller Effect in Spinel-Type Compounds"},"content":{"rendered":"

Magnetic Ordering Induces Jahn\u2013Teller Effect in Spinel-Type Compounds<\/strong><\/h1>\n

The spin\u2013orbit coupling in Jahn\u2013Teller-active Fe2+<\/sup> ions produces a novel correlation between spins, orbitals, and lattice distortions<\/em><\/p>\n

The Jahn\u2013Teller effect is a well-explored phenomenon in solid-state physics. In a new development, researchers from Waseda University, Japan, focused on spinel-type compounds with the formula A<\/em>V\u2082O\u2084, discovering a phenomenon in which a structural phase transition occurs simultaneously with magnetic ordering in Co\u2081\u208b\u2093<\/em>Fe\u2093<\/em>V\u2082O\u2084. This innovation holds fundamental scientific interest and is expected to open new avenues for applications in quantum information.<\/strong><\/p>\n

\"\"<\/p>\n

Image title<\/strong>: Jahn\u2013Teller Effect via Magnetic Ordering \u00a0
\nImage caption<\/strong>: Researchers have discovered a new phenomenon in which a structural phase transition occurs simultaneously with magnetic ordering in Co\u2081\u208b\u2093<\/em>Fe\u2093<\/em>V\u2082O\u2084.
\nImage credit<\/strong>: Professor Takuro Katsufuji from Waseda University, Japan
\nLicense type<\/strong>: Original content
\nUsage restrictions<\/strong>: Cannot be reused without permission.<\/p>\n

The Jahn\u2013Teller effect, proposed by Jahn and Teller in 1937, describes how molecules or crystals with degenerate electronic orbitals can lower their total energy by distorting their structure. This distortion lifts the degeneracy, stabilizing certain orbitals that become occupied by electrons. While many materials exhibiting this effect have been found, the involvement of spin\u2014the source of magnetism\u2014has rarely been observed because magnetic ordering usually occurs at much lower temperatures than structural distortions caused by the Jahn\u2013Teller effect.<\/p>\n

In a breakthrough study, a team of researchers, led by Professor Takuro Katsufuji, including Master\u2019s students Minato Nakano and Taichi Kobayashi, all from the Department of Physics, Waseda University, Japan, has discovered a new phenomenon in which magnetic ordering induces the Jahn\u2013Teller effect, where spin\u2013orbit coupling\u2014the coupling between electron spin and orbital angular momentum\u2014plays a crucial role. Their findings were published in the journal Physical Review Letters<\/em><\/a> on October 29, 2025.<\/p>\n

\u201cOur group has been investigating degenerate orbitals and their coupling with the spin of electrons in materials. So far, we have found various compounds that exhibit orbital ordering, a phase transition in which electrons begin to occupy specific orbitals. During this research, we identified a new phenomenon in which a structural phase transition occurs simultaneously with magnetic ordering in Co<\/em>\u2081\u208b\u2093Fe\u2093V\u2082O\u2084<\/em>,<\/em>\u201d highlights Katsufuji.<\/p>\n

The researchers notably focused on spinel-type compounds with the formula A<\/em>V\u2082O\u2084. In FeV\u2082O\u2084, Fe\u00b2\u207a ions exhibit a Jahn\u2013Teller distortion from cubic to tetragonal symmetry, whereas CoV\u2082O\u2084, lacking orbital degeneracy in Co\u00b2\u207a, does not. By studying single crystals of Co\u2081\u208b\u2093<\/em>Fe\u2093<\/em>V\u2082O\u2084 with varying x<\/em>, the team observed that the Jahn\u2013Teller structural transition occurs at the temperature at which magnetic ordering sets in, while the magnitude of the Jahn\u2013Teller distortion decreases with decreasing Fe content. These results establish that magnetic ordering can trigger Jahn\u2013Teller distortions through spin\u2013orbit coupling. This behavior can also be reproduced by a model that accounts for doubly degenerate orbitals coupled with a lattice distortion and magnetization.<\/p>\n

The doubly degenerate eg<\/sub><\/em> states of the d<\/em> orbitals in Fe2+<\/sup> form a typical two-level system in quantum mechanics. The fact that they can be controlled by magnetic fields below one tesla suggests potential applications in quantum information. Currently, controlling or reading out the state of a single Fe2+<\/sup> ion is difficult. However, by reducing the number of Fe2+<\/sup> ions in the crystal, it may become possible to control and read out the state of a single Fe2+<\/sup> ion using a magnetic field. This could open the door to applications in quantum information. However, to apply the proposed novelty to quantum information, it is necessary to reduce the number of Fe2+<\/sup> ions and measure the magnetism of a single Fe2+<\/sup> ion, requiring technological development. \u00a0<\/p>\n

Katsufuji points out the exciting theoretical breakthroughs that could emerge from their work. \u201cInterestingly, by substituting the V in <\/em>FeV<\/em>\u2082O\u2084<\/em> with a non-magnetic ion instead of replacing Fe with Co, the ordering of Fe spins can be suppressed. This is expected to create a new state of matter where orbital\u2013spin coupling exists, but both are simultaneously frustrated. Such a state, in which these two degrees of freedom are entangled and fluctuate together, is unprecedented. It holds fundamental scientific interest and promises novel applications in quantum information.\u201d<\/em><\/p>\n

Reference<\/strong><\/p>\n\n\n\n\n\n\n\n\n
\n

Title of original paper:<\/p>\n<\/td>\n

\n

Coupling between Orbital and Spin Degrees of Freedom in Jahn-Teller Ions for Co1\u2212x<\/em><\/sub>Fex<\/sub><\/em>V2<\/sub>O4<\/sub><\/p>\n<\/td>\n<\/tr>\n

\n

Authors<\/p>\n<\/td>\n

\n

Minato Nakano1<\/sup>, Taichi Kobayashi1<\/sup>, and Takuro Katsufuji1,2<\/sup><\/p>\n<\/td>\n<\/tr>\n

\n

Affiliations<\/p>\n<\/td>\n

\n

1<\/sup>Department of Physics, Waseda University, Japan<\/p>\n

2<\/sup>Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, Japan<\/p>\n<\/td>\n<\/tr>\n

Latest Article Publication Date:<\/td>\n\n

29 October 2025<\/em><\/p>\n<\/td>\n<\/tr>\n

\n

Journal:<\/p>\n<\/td>\n

\n

Physical Review Letters<\/em><\/p>\n<\/td>\n<\/tr>\n

\n

DOI:<\/p>\n<\/td>\n

\n

10.1103\/5kwm-sljw<\/a><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

About Professor Takuro Katsufuji<\/a> from Waseda University, Japan<\/strong><\/p>\n

Takuro Katsufuji is a Professor in the Department of Physics at Waseda University, Japan. He is also associated with the Kagami Memorial Research Institute for Materials Science and Technology at the same university. He obtained a Doctor of Science degree from the University of Tokyo in 1997. His research interests include strongly correlated electron systems, the search for new materials, and optical properties of materials. Prof. Katsufuji has authored more than 200 research articles on these topics and has received about 10,000 citations. He is a member of the American Physical Society and the Physical Society of Japan.<\/p>\n","protected":false},"excerpt":{"rendered":"

Magnetic Ordering Induces Jahn\u2013Teller Effect in Spinel-Type Compounds The spin\u2013orbit coupling in Jahn\u2013Teller-a […]<\/p>\n","protected":false},"author":1,"featured_media":86765,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[81,117],"tags":[358,178],"class_list":["post-86757","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","category-topic","tag-pressrelease-en","tag-research-en"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/posts\/86757","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/comments?post=86757"}],"version-history":[{"count":2,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/posts\/86757\/revisions"}],"predecessor-version":[{"id":86762,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/posts\/86757\/revisions\/86762"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/media\/86765"}],"wp:attachment":[{"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/media?parent=86757"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/categories?post=86757"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.waseda.jp\/top\/en\/wp-json\/wp\/v2\/tags?post=86757"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}