{"id":40,"date":"2021-08-27T19:48:15","date_gmt":"2021-08-27T23:48:15","guid":{"rendered":"https:\/\/sites.nd.edu\/xliu\/?page_id=40"},"modified":"2021-09-10T21:18:04","modified_gmt":"2021-09-11T01:18:04","slug":"research","status":"publish","type":"page","link":"https:\/\/sites.nd.edu\/xliu\/research\/","title":{"rendered":"Research"},"content":{"rendered":"\n<p class=\"has-yellow-color has-text-color has-medium-font-size\"><strong>Overview<\/strong><\/p>\n\n\n\n<p>Our research is focused on the fundamental physics of emerging quantum electronic matter. Compared to conventional electronic materials such as silicon, exotic states of matter showing macroscopic quantum behaviors and broken symmetries can emerge from strong interactions and correlations among basic particles in the so-called quantum materials. In our group, materials of interest include (but are not limited to)<\/p>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-top is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-top is-layout-flow wp-block-column-is-layout-flow\">\n<ul class=\"wp-block-list\" id=\"block-622a7523-b53b-4c20-8f5f-0a18955f7cd1\"><li>High-temperature superconductors<\/li><li>Candidate topological superconductors<\/li><li>Electron-pair density wave materials<\/li><li>Magnetic topological insulators<\/li><li>2D van der Waals heterostructures<\/li><li>Artificial quantum systems crafted by single atom\/molecule manipulations<\/li><li>Fully synthetic low-dimensional electronic materials and their derivatives<\/li><\/ul>\n<\/div>\n<\/div>\n\n\n\n<p class=\"has-yellow-color has-text-color has-medium-font-size\"><strong>Approaches<\/strong><\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p>We measure electronic characteristics using scanning tunneling microscopy and spectroscopy (STM\/STS). The unparalleled sub-atomic imaging precision combined with the sub-meV energy resolution at sub-kelvin temperatures make STM\/STS a powerful and unique tool in condensed matter research.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"587\" height=\"503\" src=\"http:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/STM.png\" alt=\"\" class=\"wp-image-354\" srcset=\"https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/STM.png 587w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/STM-300x257.png 300w\" sizes=\"auto, (max-width: 587px) 85vw, 587px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p>We determine momentum-space electronic structures by examining quasiparticle interference patterns using spectroscopic-imaging STM. This allows the extraction of band dispersions, symmetries of superconducting order parameters, etc.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"771\" src=\"http:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/QPI-1-1024x771.png\" alt=\"\" class=\"wp-image-368\" srcset=\"https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/QPI-1-1024x771.png 1024w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/QPI-1-300x226.png 300w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/QPI-1-768x578.png 768w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/QPI-1-1200x904.png 1200w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/QPI-1.png 1243w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p>We visualize and examine broken symmetries and heterogeneities in superconducting condensate using scanned Josephson tunneling microscopy (SJTM). While conventional STM only probes quasiparticle excitations via single-electron tunneling, Josephson tunneling of electron pairs provides direct access to superfluid density.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1002\" height=\"994\" src=\"http:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/SJTM.png\" alt=\"\" class=\"wp-image-363\" srcset=\"https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/SJTM.png 1002w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/SJTM-300x298.png 300w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/SJTM-150x150.png 150w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/SJTM-768x762.png 768w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p>We create artificial quantum systems by on-surface manipulation of single atoms and molecules using STM for experimental quantum simulation. This allows the creation of on-demand electronic structures that are otherwise unavailable.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"750\" height=\"709\" src=\"http:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/CO-maniulations.png\" alt=\"\" class=\"wp-image-378\" srcset=\"https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/CO-maniulations.png 750w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/CO-maniulations-300x284.png 300w\" sizes=\"auto, (max-width: 750px) 85vw, 750px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p>We explore the synthesis of low-dimensional electronic materials via molecular beam epitaxy and the fabrication of novel 2D heterostructures. By circumventing thermodynamic constraints, those materials\/heterostructures may offer entirely new properties and exhibit new quantum phenomena.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"345\" height=\"345\" src=\"http:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/MBE-and-heter.png\" alt=\"\" class=\"wp-image-383\" srcset=\"https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/MBE-and-heter.png 345w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/MBE-and-heter-300x300.png 300w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/MBE-and-heter-150x150.png 150w\" sizes=\"auto, (max-width: 345px) 85vw, 345px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p>We tune material properties both chemically and mechanically in ultrahigh vacuum chambers to gain access to different regions of the phase space.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"701\" height=\"556\" src=\"http:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/strain-and-chem.png\" alt=\"\" class=\"wp-image-389\" srcset=\"https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/strain-and-chem.png 701w, https:\/\/sites.nd.edu\/xliu\/files\/2021\/09\/strain-and-chem-300x238.png 300w\" sizes=\"auto, (max-width: 701px) 85vw, 701px\" \/><\/figure>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Overview Our research is focused on the fundamental physics of emerging quantum electronic matter. Compared to conventional electronic materials such as silicon, exotic states of matter showing macroscopic quantum behaviors and broken symmetries can emerge from strong interactions and correlations among basic particles in the so-called quantum materials. In our group, materials of interest include &hellip; <a href=\"https:\/\/sites.nd.edu\/xliu\/research\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Research&#8221;<\/span><\/a><\/p>\n","protected":false},"author":4039,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"ngg_post_thumbnail":0,"footnotes":""},"class_list":["post-40","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/pages\/40","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/users\/4039"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/comments?post=40"}],"version-history":[{"count":23,"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/pages\/40\/revisions"}],"predecessor-version":[{"id":440,"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/pages\/40\/revisions\/440"}],"wp:attachment":[{"href":"https:\/\/sites.nd.edu\/xliu\/wp-json\/wp\/v2\/media?parent=40"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}