Ladewig Chad, Anwar Fatima, Lee Veronica, Kelber Jeffry A, Shah Syed Q A, Dowben Peter A
Department of Chemistry , University of North Texas , Denton , Texas 76203 , United States.
Department of Physics and Astronomy , University of Nebraska-Lincoln , Lincoln , Nebraska 68588 , United States.
Langmuir. 2019 Nov 19;35(46):14797-14803. doi: 10.1021/acs.langmuir.9b02654. Epub 2019 Nov 8.
Heterostructures consisting of 10 Å thick chromia films and 50 Å thick titania films display significant exchange bias at and above room temperature. Chromia films ∼10 Å thick were deposited by molecular beam epitaxy (MBE) of Cr at room temperature in ultrahigh vacuum on 50 Å thick TiO(111) films ( < 0.3) also deposited epitaxially by MBE on AlO(0001). Cr deposition yields increased Ti(III) formation in the titania substrate and the formation of a CrO overlayer, without Cr/Ti interfacial mixing, as determined by in situ photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). In situ low-energy electron diffraction (LEED) and XPS data indicate that the chromia overlayer is hexagonally ordered and ∼10 Å thick. Longitudinal and polar magneto-optic Kerr effect (MOKE) measurements at 285-315 K provide evidence of strong exchange bias between the boundary layer magnetization of chromia and the ferromagnetic substrate. These data demonstrate the robust room-temperature interaction of the boundary layer magnetization of a multiferroic antiferromagnet with a d ferromagnetic substrate.
由10埃厚的氧化铬薄膜和50埃厚的二氧化钛薄膜组成的异质结构在室温及室温以上表现出显著的交换偏置。通过在超高真空下于室温对Cr进行分子束外延（MBE），在同样通过MBE外延生长在AlO(0001)上的50埃厚TiO(111)薄膜（< 0.3）上沉积约10埃厚的氧化铬薄膜。原位光电子能谱（XPS）和电子能量损失谱（EELS）测定表明，Cr沉积会使二氧化钛衬底中Ti(III)的形成增加，并形成CrO覆盖层，且不存在Cr/Ti界面混合。原位低能电子衍射（LEED）和XPS数据表明，氧化铬覆盖层呈六方有序，厚度约为10埃。在285 - 315 K下进行的纵向和极化磁光克尔效应（MOKE）测量提供了氧化铬边界层磁化与铁磁衬底之间存在强交换偏置的证据。这些数据证明了多铁性反铁磁体的边界层磁化与d铁磁衬底在室温下存在稳健的相互作用。
