Abstract
Multiferroicspermitthemagneticcontroloftheelectricpolarizationandelectriccontrolofthemagnetization1{8.Thesestaticmagnetoelec-tric(ME)e ectsareofenormousinterest:Theabilitytoreadandwriteamagneticstatecurrent-freebyanelectricvoltagewouldprovideahugetechnologicaladvantage5{8.DynamicoropticalMEe ectsareequallyinterestingbecausetheygiverisetounidirectionallightpropagationasrecentlyobservedinlow-temperaturemultifer-roics9{14.Thisphenomenon,ifrealizedatroomtemperature,wouldallowthedevelopmentofop-ticaldiodeswhichtransmitunpolarizedlightinone,butnotintheoppositedirection.Here,wereportstrongunidirectionaltransmissionintheroom-temperaturemultiferroicBiFeO3overthegigahertz{terahertzfrequencyrange.Support-ingtheoryattributestheobservedunidirectionaltransmissiontothespin-currentdrivendynamicMEe ect.These ndingsareanimportantsteptowardtherealizationofopticaldiodes,supple-mentedbytheabilitytoswitchthetransmissiondirectionwithamagneticorelectric eld.
