{"id":71593,"date":"2024-11-26T16:36:21","date_gmt":"2024-11-26T14:36:21","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=71593"},"modified":"2024-11-26T16:36:21","modified_gmt":"2024-11-26T14:36:21","slug":"these-geoffrey-lezier","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/a-la-une\/these-geoffrey-lezier.html","title":{"rendered":"Geoffrey LEZIER's thesis: \"New high-speed THz sources using broadband inverse Spin Hall emitters: new control modes for THz Spintronic Emitters\" on 13\/12 14:00"},"content":{"rendered":"<div id='layer_slider_1'  class='avia-layerslider main_color avia-shadow  avia-builder-el-0  el_before_av_heading  avia-builder-el-first  container_wrap sidebar_right'  style='height: 261px;'  ><div id=\"layerslider_58_uan3j3kp1ety\" data-ls-slug=\"homepageslider\" class=\"ls-wp-container fitvidsignore ls-selectable\" style=\"width:1140px;height:260px;margin:0 auto;margin-bottom: 0px;\"><div class=\"ls-slide\" data-ls=\"duration:6000;transition2d:5;\"><img loading=\"lazy\" decoding=\"async\" width=\"2600\" height=\"270\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1.jpg\" class=\"ls-bg\" alt=\"\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1.jpg 2600w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-300x31.jpg 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-768x80.jpg 768w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-1030x107.jpg 1030w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-1500x156.jpg 1500w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-705x73.jpg 705w\" sizes=\"auto, (max-width: 2600px) 100vw, 2600px\" \/><ls-layer style=\"font-size:14px;text-align:left;font-style:normal;text-decoration:none;text-transform:none;font-weight:700;letter-spacing:0px;border-style:solid;border-color:#000;background-position:0% 0%;background-repeat:no-repeat;width:180px;height:30px;left:0px;top:231px;line-height:32px;color:#ffffff;border-radius:6px 6px 6px 6px;padding-left:50px;background-color:rgba(0, 0, 0, 0.57);\" class=\"ls-l ls-ib-icon ls-text-layer\" data-ls=\"minfontsize:0;minmobilefontsize:0;\"><i class=\"fa fa-quote-right\" style=\"color:#ffffff;margin-right:0.8em;font-size:1em;transform:translateY( -0.125em );\"><\/i>ACTUALITES<\/ls-layer><\/div><\/div><\/div><div id='after_layer_slider_1'  class='main_color av_default_container_wrap container_wrap sidebar_right'  ><div class='container av-section-cont-open' ><div class='template-page content  av-content-small alpha units'><div class='post-entry post-entry-type-page post-entry-71593'><div class='entry-content-wrapper clearfix'>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-k5dohoxw-e0e07bcc4f9a64b5044ce40624ffd18d\">\n#top .av-special-heading.av-k5dohoxw-e0e07bcc4f9a64b5044ce40624ffd18d{\nmargin:0 0 10px 0;\npadding-bottom:4px;\n}\nbody .av-special-heading.av-k5dohoxw-e0e07bcc4f9a64b5044ce40624ffd18d .av-special-heading-tag .heading-char{\nfont-size:25px;\n}\n.av-special-heading.av-k5dohoxw-e0e07bcc4f9a64b5044ce40624ffd18d .av-subheading{\nfont-size:15px;\n}\n<\/style>\n<div  class='av-special-heading av-k5dohoxw-e0e07bcc4f9a64b5044ce40624ffd18d av-special-heading-h4  avia-builder-el-1  el_after_av_layerslider  el_before_av_hr  avia-builder-el-first  av-linked-heading'><h4 class='av-special-heading-tag'  itemprop=\"headline\"  >Geoffrey LEZIER's thesis: \"New high-speed THz sources using broadband inverse Spin Hall emitters: new control modes for THz Spintronic Emitters\" on 13\/12 14:00<\/h4><div class=\"special-heading-border\"><div class=\"special-heading-inner-border\"><\/div><\/div><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-18u73nj-dad6a947580930e400fc42ba200e80f1\">\n#top .hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1{\nmargin-top:5px;\nmargin-bottom:5px;\n}\n.hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1 .hr-inner{\nwidth:100%;\n}\n<\/style>\n<div  class='hr av-18u73nj-dad6a947580930e400fc42ba200e80f1 hr-custom  avia-builder-el-2  el_after_av_heading  el_before_av_textblock  hr-left hr-icon-no'><span class='hr-inner inner-border-av-border-thin'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<section  class='av_textblock_section av-jriy64i8-fd5f2e9d63bf552d6910d12f255eb26e'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" >\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-13ewzjw-68e036126b913e5028f77311dc66b825\">\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825{\ncolor:#bfbfbf;\nborder-color:#bfbfbf;\n}\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825 .av-icon-char{\nfont-size:60px;\nline-height:60px;\n}\n<\/style>\n<span  class='av_font_icon av-13ewzjw-68e036126b913e5028f77311dc66b825 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue8c9' data-av_iconfont='entypo-fontello' ><\/span><\/span>\n<p><strong>Geoffrey LEZIER's thesis<br \/>\n<\/strong><\/p>\n<p>Defence: 13 December 14:00<strong><br \/>\n<\/strong>IEMN Amphitheatre<\/p>\n<\/div><\/section>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-jtefqx33-6db969b2e204313ebd62331ed4fc69ec\">\n#top .av_textblock_section.av-jtefqx33-6db969b2e204313ebd62331ed4fc69ec .avia_textblock{\nfont-size:15px;\n}\n<\/style>\n<section  class='av_textblock_section av-jtefqx33-6db969b2e204313ebd62331ed4fc69ec'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div  class='hr av-kjh3zw-4dff888f744b728a1aca9b3a0971493a hr-default  avia-builder-el-6  avia-builder-el-no-sibling'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<h5><strong><span style=\"color: #800000;\">Jury<\/span><\/strong><\/h5>\n<table width=\"100%\">\n<tbody>\n<tr>\n<td>Nicolas TIERCELIN<\/td>\n<td>Universit\u00e9 de Lille<\/td>\n<td>Directeur de th\u00e8se<\/td>\n<\/tr>\n<tr>\n<td>Mr Jon GORCHON<\/td>\n<td>Jean Larmour Institute<\/td>\n<td>Rapporteur<\/td>\n<\/tr>\n<tr>\n<td>Fr\u00e9d\u00e9ric MAZALEYRAT<\/td>\n<td>ENS Paris -Saclay\/SATIE<\/td>\n<td>Rapporteur<\/td>\n<\/tr>\n<tr>\n<td>Ms Sarah HOUVER<\/td>\n<td>Universit\u00e9 Paris Cit\u00e9 - Quantum Materials and Phenomena Laboratory<\/td>\n<td>Examinatrice<\/td>\n<\/tr>\n<tr>\n<td>Mr Christophe DELERUE<\/td>\n<td>IEMN<\/td>\n<td>Examinateur<\/td>\n<\/tr>\n<tr>\n<td>Mr Mathias VANWOLLEGHEM<\/td>\n<td>IEMN<\/td>\n<td>Examinateur<\/td>\n<\/tr>\n<tr>\n<td>Mr Jean-Fran\u00e7ois LAMPIN<\/td>\n<td>IEMN<\/td>\n<td>Invit\u00e9<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h5><strong><span style=\"color: #800000;\">\u00a0<\/span><\/strong>Summary:<\/h5>\n<p>The development of THz transmission technologies quickly came up against numerous limitations, particularly in terms of bandwidth and transmission power. The conventional technologies used until now are no longer suitable for applications requiring very wide bandwidths without losses. In addition, THz polarisation control is generally not easy to implement, despite the many potential applications in ellipsometry or telecommunications. This manuscript presents the emergence of THz spintronic transmitters, which use the spin's degree of freedom to produce a very broadband and uninterrupted THz emission over a range that can exceed 30 THz. Using the inverse spin Hall effect, these transmitters generate linear pulsed THz waves whose polarisation can be easily controlled by manipulating the magnetisation in the devices. These properties, hitherto little exploited, have led to the development of new device architectures to improve control. The standard structure of these emitters, a nanometric stack of W|FeCoB|Pt, is generally polarised and oriented using permanent magnetic fields, requiring mechanical rotation to cause the polarisation to rotate. By creating a device with magnetic layers coupled by exchange interactions, it is possible to induce uniaxial magnetic anisotropy in the structure. This new emitter configuration, whose active layers are then W|FeCo|TbCo2|FeCo|Pt, enables polarisation to be controlled over 360\u00b0 using a scalar fixed magnetic field, according to the Stoner-Wohlfarth model. However, this principle of polarisation control, although innovative, still requires the use of strong magnetic fields, generally produced by bulky electromagnets. The magnetic structure developed previously also turns out to be a magneto-elastic configuration, sensitive to mechanical stress. So, by coupling this new structure with a piezoelectric element, it is possible to achieve magnetoelectric control of THz spintronic transmitters. The development of an emitter with uniaxial anisotropy deposited on a PMN-PT piezoelectric substrate has made it possible to establish THz polarisation control over a range of 90\u00b0, solely by applying an electric field to the device. Until now, polarisation control has been static. Dynamic polarisation control would therefore be a clear advantage in ellipsometry or communications systems. For example, it is possible to modulate the polarisation in transmitters using sinusoidal magnetic fields generated by coils. This modulation is also facilitated by involving the Spin Reorientation Transition in the anisotropic structures, to drastically increase magnetic sensitivity and enable modulation at a record frequency of 10 MHz. Finally, these spintronic emitters are integrated into optical and THz cavities in order to mitigate the main shortcoming of these emitters, their general lack of efficiency compared with standard THz generation methods. In addition, the emitters are also deposited on optical fibres, so that they can be easily integrated and used on conventional optical systems. This integration also brings its own set of challenges, both in terms of manufacture, but also when used in high-power regimes.<\/p>\n<h5 align=\"justify\"><strong>Abstract:<\/strong><\/h5>\n<p>The development of THz transmission technologies quickly came up against numerous limitations, particularly in terms of bandwidth and transmission power. The conventional technologies used until now are no longer suitable for applications requiring very wide bandwidths without losses. In addition, THz polarisation control is generally not easy to implement, despite the many potential applications in ellipsometry or telecommunications. This manuscript presents the emergence of THz spintronic transmitters, which use the spin's degree of freedom to produce a very broadband and uninterrupted THz emission over a range that can exceed 30 THz. Using the inverse spin Hall effect, these transmitters generate linear pulsed THz waves whose polarisation can be easily controlled by manipulating the magnetisation in the devices. These properties, hitherto little exploited, have led to the development of new device architectures to improve control. The standard structure of these emitters, a nanometric stack of W|FeCoB|Pt, is generally polarised and oriented using permanent magnetic fields, requiring mechanical rotation to cause the polarisation to rotate. By creating a device with magnetic layers coupled by exchange interactions, it is possible to induce uniaxial magnetic anisotropy in the structure. This new emitter configuration, whose active layers are then W|FeCo|TbCo2|FeCo|Pt, enables polarisation to be controlled over 360\u00b0 using a scalar fixed magnetic field, according to the Stoner-Wohlfarth model. However, this principle of polarisation control, although innovative, still requires the use of strong magnetic fields, generally produced by bulky electromagnets. The magnetic structure developed previously also turns out to be a magneto-elastic configuration, sensitive to mechanical stress. So, by coupling this new structure with a piezoelectric element, it is possible to achieve magnetoelectric control of THz spintronic transmitters. The development of an emitter with uniaxial anisotropy deposited on a PMN-PT piezoelectric substrate has made it possible to control THz polarisation over a range of 90\u00b0, solely by applying an electric field to the device. Until now, polarisation control has been static. Dynamic polarisation control would therefore be a clear advantage in ellipsometry or communications systems. For example, it is possible to modulate the polarisation in transmitters using sinusoidal magnetic fields generated by coils. This modulation is also facilitated by involving the Spin Reorientation Transition in the anisotropic structures, to drastically increase magnetic sensitivity and enable modulation at a record frequency of 10 MHz. Finally, these spintronic emitters are integrated into optical and THz cavities in order to mitigate the main shortcoming of these emitters, their general lack of efficiency compared with standard THz generation methods. In addition, the emitters are also deposited on optical fibres, so that they can be easily integrated and used on conventional optical systems. This integration also brings its own set of challenges, both in terms of manufacture, but also when used in high-power regimes.<\/p>\n<\/div><\/section>","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":71447,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,8,319,87,65,84],"tags":[],"class_list":["post-71593","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-a-la-une","category-actualites","category-actualites2022","category-agenda-en","category-agenda","category-agenda-en-en"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/71593","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=71593"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/71593\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/71447"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=71593"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=71593"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=71593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}