SABON NAU'IN MAGANAƊISU YANA AIKI A ZAFIN ƊAKI

Electrons suna ɗauke da caji, amma kuma da spin, wani ƙaramin maganaɗisu na ciki da ke nuna “sama” ko “ƙasa”. Spintronics na nufin amfani da wannan spin don adanawa da sarrafa bayanai. A shekarun baya-bayan nan, masana kimiyyar lissafi sun gano kayan maganaɗisu masu wata siffa ta musamman: ba su da jimillar magnetisation, amma makamashin electrons ɗinsu har yanzu ya dogara ne kan spin ɗinsu, ta hanyar da ke canzawa da alƙiblar da suke motsawa. Wannan “spin splitting” ba ya dogara ga tasirin relativity, abin da ke sa ta zama babba.

A cikin wasu daga cikin waɗannan kayan, da ake kira altermagnets, tsarin yana da daidaito: electron da ke motsawa ta wata hanya da wanda ke motsawa ta hanyar da ke gaba da ita suna ganin spin iri ɗaya. A cikin p-wave magnets, akasin haka ne: juya alƙiblar motsi kuma spin ma ya juya. Har zuwa yanzu, p-wave magnets da aka bayar da rahoto suna aiki ne kawai ƙasa da zafin liquid nitrogen.

Karkace da ke ɓoye a cikin sanannen lu’ulu’u

Kaiwen Shen, Xianzhe Chen, Libor Šmejkal da abokan aikinsu a Jami’ar Fudan a Shanghai, Cibiyoyin Max Planck biyu a Dresden, da wasu cibiyoyi a China da Jamhuriyar Czech, sun juya zuwa bismuth ferrite (BiFeO₃). Ɗaya ne daga cikin “multiferroics” da aka fi nazari, kayan da ke da maganaɗisu kuma ferroelectric — suna ɗauke da electric polarisation na ciki. Yana riƙe da tsarin maganaɗisu har zuwa kusan kelvin 640 (sama da zafin ɗaki nesa ba kusa ba) da ferroelectric har zuwa kelvin 1,100.

A cikinsa, magnetic moments na atom ɗin ƙarfe ba su jeru a layi ɗaya ba: suna juyawa mataki-mataki a kan wani karkace, da ake kira cycloid. Ƙungiyar ta nuna cewa wannan karkace, shi kaɗai, yana samar da maganaɗisu na p-wave — hanyar da suka bayyana a matsayin wadda aka yi watsi da ita a baya.

Ka’ida, sannan laser

• Lissafai na electrons na lu’ulu’un sun nuna tsarin spin na p-wave mai tsabta, da spin splitting na kusan millielectronvolts 100. Ƙara tasirin relativity bai canza shi ba sosai: tasirin ya fito ne daga tsarin maganaɗisu kansa.
• Idan karkacen ya juya ta ɗayan hanya — hagu maimakon dama — tsarin spin yana juyawa.
• A ɗakin gwaji, sun girma fim na nanometer 100 na bismuth ferrite kuma sun ɗauki hoton karkacen maganaɗisunsa da wata na’urar jin quantum mai bakin lu’u-lu’u (diamond).
• Don karanta spins, sun haskaka laser mai circular polarisation a kan fim ɗin. Hasken da ke juyawa ta wata hanya yana motsa electrons na wani spin fiye da na ɗayan, yana samar da ƙaramin wutar lantarki wanda alamarsa ke bin alƙiblar spin. Yayin da suke juya samfurin, wutar ta kai ƙololuwa daidai a alƙiblar da aka yi hasashe ga spin polarisation na p-wave. Duk waɗannan ma’aunai an yi su ne a zafin ɗaki, a sararin iska.

Juya spins da voltage

Babbar siffar: a cikin bismuth ferrite, hannun karkacen yana kulle da electric polarisation. Juya ɗaya, ɗayan ma zai bi.

Ƙungiyar ta tura bugun lantarki na kusan kilovolts 300 a kowane centimeter ta cikin fim ɗin. Polarisation ta juya, karkacen ya canza hannu, kuma wutar da laser ya haifar ta canza alama: tabbatacciya bayan wani bugu, korarriya (negative) bayan bugun da ke gaba da shi. Idan aka zana ta da filin da aka shafa, wutar ta zana hysteresis loop da ya dace da juyawar polarisation na lu’ulu’un. Canjin yana iya komawa kuma yana tsayawa a wurinsa bayan bugun.

Bugun lantarki yana juya polarisation da hannun karkacen (a); na’urar (b); wutar spin tana juya alama (c) kuma tana bin hysteresis loop idan aka kwatanta da filin lantarki (d). — Figure 3, Shen et al. (2026), arXiv:2610.12892.

Daga sanyi zuwa kan tebur

Marubutan sun gabatar da shi a matsayin maganaɗisu mai spin splitting na odd-parity da voltage ke sarrafawa a zafin ɗaki, kuma suna ganinsa a matsayin hanya zuwa na’urorin spintronics masu ƙarancin amfani da makamashi. Sakamakon ya fito ne daga siraran fim a ɗakin gwaji; ba a nuna wata na’ura ba tukuna fiye da juyawar siginar da aka auna.