{"id":2378,"date":"2010-06-18T16:31:09","date_gmt":"2010-06-18T14:31:09","guid":{"rendered":"http:\/\/localhost\/azgad\/wordpress\/?p=2378"},"modified":"2010-07-09T08:06:46","modified_gmt":"2010-07-09T06:06:46","slug":"molecular-blockade","status":"publish","type":"post","link":"https:\/\/azgad.com\/?p=2378","title":{"rendered":"Molecular blockade"},"content":{"rendered":"

.
\nArtificial \u2018molecules\u2019 with an asymmetric structure can control the
\n flow of electrons in semiconductor materials<\/strong>
\n.
\nNanoscale devices confine electrons and enable manipulation of electron
\nspin\u2014an inherent property akin to the direction in which the particle is rotating.
\n An unexpected mechanism for this control in asymmetric structures has now
\nbeen reported by Keiji Ono at the RIKEN Advanced Science Institute, Wako,
\nin collaboration with a team of researchers from Japan and Taiwan.
\n.
\nArtificial systems that trap electrons in a tiny volume can display many
\n of the properties of atoms because they create an analogous series of
\n discrete electron energy levels. \u201cOne example is the Zeeman Effect in
\n which an applied magnetic field splits a single electron energy level
\ninto two, depending on its spin,\u201d explains Ono.
\n.
\nTaking this analogy further, two closely spaced \u2018artificial atoms\u2019 can
\n behave like an artificial molecule. In principle, it is possible to transfer an
\nelectron between these atoms by tuning the energy level of an electron
\n in one atom to that of the second by, for example, applying an electric
\nfield. Indeed, this phenomenon, known as resonant tunneling, occurs in
\n artificial molecules consisting of two identical atoms. Ono and his team
\nshowed, however, that the situation is not so simple in artificial
\nmolecules comprising two different atoms.
\n.<\/p>\n

They investigated a structure that was a stack of alternating layers of
\n semiconductor. Electrons become trapped in the semiconductor with
\n the smaller bandgap by the surrounding layers of wide-bandgap
\nmaterial. The top \u2018atom\u2019 was 7.5 nanometers thick and made of indium
\ngallium arsenide. A 6.5-nanometer barrier separated this from the
\n second atom: 10 nanometers of gallium arsenide. Etched pillars
\n with a diameter of less than one micrometer confined the electrons
\n in the transverse direction.
\n.
\nThe difference in size and composition meant that the Zeeman Effect
\n was stronger in the top atom than the bottom one. This made it impossible to
\n align both of the Zeeman-split levels in the two atoms at the same time. Ono
\nand colleagues demonstrated that because of this, when an energy state
\nfrom one atom is aligned with one in the second, the electron
\n flow through the molecule reduces, an effect they call spin
\n blockade. The flow increased when they tuned the two Zeeman
\nlevels in one atom to the midpoint of those in the other atom.
\n.
\n\u201cThis finding can be used as a basic tool for selecting, filtering, or initializing
\n an individual electron spin,\u201d comments Ono. \u201cI hope this can be applied to
\nquantum information technology.\u201d <\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

. Artificial \u2018molecules\u2019 with an asymmetric structure can control the flow of electrons in semiconductor materials . Nanoscale devices confine electrons and enable manipulation of electron spin\u2014an inherent property akin to the direction in which the particle is rotating. An unexpected mechanism for this control in asymmetric structures has now been reported by Keiji Ono … <\/p>\n

\u05d4\u05de\u05e9\u05d9\u05db\u05d5 \u05d1\u05e7\u05e8\u05d9\u05d0\u05d4<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[10],"tags":[513,49,260],"class_list":["post-2378","post","type-post","status-publish","format-standard","hentry","category-10","tag-513","tag-49","tag-260","nodate","item-wrap"],"_links":{"self":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/2378","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2378"}],"version-history":[{"count":14,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/2378\/revisions"}],"predecessor-version":[{"id":2462,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/2378\/revisions\/2462"}],"wp:attachment":[{"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2378"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2378"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2378"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}