{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T14:32:53Z","timestamp":1791988373763,"version":"4.4.0"},"reference-count":48,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"6505","funder":[{"name":"JSPS KAKENHI","award":["JP19K03722"],"award-info":[{"award-number":["JP19K03722"]}]},{"name":"JSPS KAKENHI","award":["JP18H01165"],"award-info":[{"award-number":["JP18H01165"]}]},{"name":"JSPS KAKENHI","award":["JP16H06345"],"award-info":[{"award-number":["JP16H06345"]}]},{"name":"JSPS KAKENHI","award":["JP19H01829"],"award-info":[{"award-number":["JP19H01829"]}]},{"name":"JSPS KAKENHI","award":["JP19H02683"],"award-info":[{"award-number":["JP19H02683"]}]},{"name":"JSPS KAKENHI","award":["JP19H02594"],"award-info":[{"award-number":["JP19H02594"]}]},{"name":"JSPS KAKENHI","award":["JP18H01163"],"award-info":[{"award-number":["JP18H01163"]}]},{"name":"AIST-UTokyo OPERANDO-OIL"},{"name":"JSPS KAKENHI","award":["JP19H00651"],"award-info":[{"award-number":["JP19H00651"]}]},{"name":"JSPS KAKENHI","award":["JP19H05825"],"award-info":[{"award-number":["JP19H05825"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Science"],"published-print":{"date-parts":[[2020,8,14]]},"abstract":"<jats:title>An elusive pocket<\/jats:title>\n                  <jats:p>\n                    Superconductivity in copper oxide materials emerges by doping a special kind of correlated state called the Mott insulator. However, studying what happens when a small concentration of charge carriers\u2014holes or electrons\u2014is added to a Mott insulator is experimentally challenging. It has been predicted that the so-called \u201cFermi pockets\u201d should become visible during experimentation, but such pockets have not been unambiguously observed. Kunisada\n                    <jats:italic>et al.<\/jats:italic>\n                    studied the unusual cuprate Ba\n                    <jats:sub>2<\/jats:sub>\n                    Ca\n                    <jats:sub>4<\/jats:sub>\n                    Cu\n                    <jats:sub>5<\/jats:sub>\n                    O\n                    <jats:sub>10<\/jats:sub>\n                    (F,O)\n                    <jats:sub>2<\/jats:sub>\n                    , which has five copper oxide planes in a unit cell, whereas most cuprates have one or two (see the Perspective by Vishik). They observed two Fermi pockets in both photoemission and quantum oscillations data, with the innermost copper oxide planes playing a crucial role.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:italic>Science<\/jats:italic>\n                    , this issue p.\n                    <jats:related-article xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"doi\" issue=\"6505\" page=\"833\" related-article-type=\"in-this-issue\" vol=\"369\" xlink:href=\"10.1126\/science.aay7311\">833<\/jats:related-article>\n                    ; see also p.\n                    <jats:related-article xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"doi\" issue=\"6505\" page=\"775\" related-article-type=\"in-this-issue\" vol=\"369\" xlink:href=\"10.1126\/science.aba9482\">775<\/jats:related-article>\n                  <\/jats:p>","DOI":"10.1126\/science.aay7311","type":"journal-article","created":{"date-parts":[[2020,8,17]],"date-time":"2020-08-17T20:34:13Z","timestamp":1597696453000},"page":"833-838","source":"Crossref","is-referenced-by-count":64,"title":["Observation of small Fermi pockets protected by clean CuO\n                    <sub>2<\/sub>\n                    sheets of a high-\n                    <i>T<\/i>\n                    <sub>c<\/sub>\n                    superconductor"],"prefix":"10.1126","volume":"369","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6538-9756","authenticated-orcid":true,"given":"So","family":"Kunisada","sequence":"first","affiliation":[{"name":"ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shunsuke","family":"Isono","sequence":"additional","affiliation":[{"name":"Department of Applied Electronics, Tokyo University of Science, Tokyo 125-8585, 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