Antiferromagnetism in UO2 thin epitaxial films

被引：29

作者：

Bao, Z. ^{[1
]}

Springell, R. ^{[2
]}

Walker, H. C. ^{[3
]}

Leiste, H. ^{[4
]}

Kuebel, K. ^{[4
]}

Prang, R. ^{[4
]}

Nisbet, G. ^{[5
]}

Langridge, S. ^{[6
]}

Ward, R. C. C. ^{[7
]}

Gouder, T. ^{[1
]}

Caciuffo, R. ^{[1
]}

Lander, G. H. ^{[1
]}

机构：

[1] European Commiss, Joint Res Ctr, Inst Transuranium Elements, D-76125 Karlsruhe, Germany

[2] Univ Bristol, Sch Phys, Interface Anal Ctr, Royal Commiss Exhibit 1851 Res Fellow, Bristol BS2 8BS, Avon, England

[3] European Synchrotron Radiat Facil, F-38043 Grenoble, France

[4] Karlsruhe Inst Technol KIT, Inst Appl Mat IAM AWP, D-76344 Eggenstein Leopoldshafen, Germany

[5] Diamond Light Source Ltd, Didcot OX11 0DE, Oxon, England

[6] Rutherford Appleton Lab, ISIS, Didcot OX11 0QX, Oxon, England

[7] Univ Oxford, Clarendon Lab, Oxford OX1 3PU, England

来源：

PHYSICAL REVIEW B | 2013年 / 88卷 / 13期

关键词：

X-RAY-SCATTERING; 2ND LENGTH SCALE; MAGNETIC-STRUCTURE; URANIUM-OXIDES; DIFFRACTION; SURFACE; NIOBIUM; GROWTH; ORIGIN;

D O I：

10.1103/PhysRevB.88.134426

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Thin films (250-4500 angstrom) of epitaxial UO2 were produced by reactive sputtering on two different substrate materials: LaAlO3 and CaF2. Using the large enhancement present with resonant x-ray scattering using photons at the uranium M-4 absorption edge, antiferromagnetic (AF) order was found in all films. The ordering temperature T-N is the same as the bulk, but the films show second-order (continuous) transitions in contrast to the first-order bulk transition. For LaAlO3-based films, an additional strong diffuse magnetic disorder is observed, which is reminiscent of the second-length scale, associated with structural disorder and/or strain. By using a formulation accounting for the strong absorption and coherent nature of the photons, the energy widths at the UM4 resonances can be related to the thickness of the AF region. The LaAlO3-based films do not order magnetically over more than similar to 600 angstrom, whereas the CaF2-based film orders throughout. Further, for thicker films (>1000 angstrom) the fitting procedure shows that the AF order is located at the top of the LaAlO3-based film. This points to the formation in thicker films of a nonmagnetic layer of UO2 adjacent to the substrate, which may have tetragonal symmetry.

引用

页数：10

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