Extrinsic origin of ferromagnetism in single crystalline LaAlO3 substrates and oxide films

Golmar, F.; Navarro, A.M. Mudarra; Torres, C.E. Rodrı́guez; Sánchez, F.; Saccone, Fabio Daniel; Claro, Paula Cecilia dos Santos; Benítez, G.; Schilardi, Patricia Laura

doi:10.1063/1.2952839

Cited by 38 publications

(21 citation statements)

References 10 publications

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“…of Fe or Ni. Therefore, strong discussion currently occurs in the literature, whether defect-induced ferromagnetism exists or is just a misinterpretation resulting from Fe contaminated samples [51]. Especially metallic a-or g-Fe clusters can occur [52].…”

Section: Exclusion Of Metallic Fe Contaminationmentioning

confidence: 98%

Defect-induced ferromagnetism in crystalline SrTiO3

Potzger

Osten

Levin

et al. 2011

Journal of Magnetism and Magnetic Materials

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Section: Exclusion Of Metallic Fe Contaminationmentioning

confidence: 98%

Defect-induced ferromagnetism in crystalline SrTiO3

Potzger

Osten

Levin

et al. 2011

Journal of Magnetism and Magnetic Materials

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“…Whether or not a magnetic order is also present at the oxygen-deficient surface of TiO 2 anatase cannot be deduced from the ARPES data presented in this paper. Note that magnetic order in thin films of TiO 2 due to oxygen vacancies was previously observed and discussed [41][42][43][44][45][46], and is thus a potential reason for the observed splitting of the d xy -bands. Further experimental work is necessary to clarify the possible magnetism at the oxygen-deficient surface of TiO 2 anatase.…”

mentioning

confidence: 89%

Engineering two-dimensional electron gases at the (001) and (101) surfaces ofTiO2anatase using light

et al. 2015

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We report the existence of metallic two dimensional electron gases (2DEGs) at the (001) and (101) surfaces of bulk-insulating TiO2 anatase due to local chemical doping by oxygen vacancies in the near-surface region. Using angle-resolved photoemission spectroscopy, we find that the electronic structure at both surfaces is composed of two occupied subbands of dxy orbital character. While the Fermi surface observed at the (001) termination is isotropic, the 2DEG at the (101) termination is anisotropic and shows a charge carrier density three times larger than at the (001) surface. Moreover, we demonstrate that intense UV synchrotron radiation can alter the electronic structure and stoichiometry of the surface up to the complete disappearance of the 2DEG. These results open a route for the nano-engineering of confined electronic states, the control of their metallic or insulating nature, and the tailoring of their microscopic symmetry, using UV illumination at different surfaces of anatase.In its pure stoichiometric form, the transition metal oxide (TMO) TiO 2 is a transparent insulator that crystallizes in mainly two different phases: rutile and anatase. Both phases have been studied extensively over the last decades, due to their photocatalytic properties discussed in several reviews [1][2][3][4]. Recently, a strong interest in the anatase phase of TiO 2 also surged, owing to its potential for applications in other research fields. For instance, networks of anatase nanoparticles are found in dye-sensitized solar cells [5,6], anatase thin films can be used as transparent conducting oxides [7], and devices based on anatase can be envisioned in spintronics [8,9]. To harness such a wide range of functionalities and guide potential applications using anatase, it is thus critical to understand its microscopic electronic structure, which will be ultimately responsible for the remarkable properties of this material. Moreover, as most applications in microelectronics or heterogeneous catalysis involve essentially the electronic states at the material's surface, it is crucial to directly measure and characterize such states.More generally, the study of two-dimensional electron gases (2DEGs) in TMO surfaces/interfaces has become a very active field of research. The archetypal example, SrTiO 3 -based heterostructures, display many fundamentally interesting properties [10][11][12], such as field-effect induced insulator-to-superconductor transitions [13], magnetism [14] and the coexistence of magnetism and superconductivity [15]. More recently, the discoveries of 2DEGs at the bare (001), (110) and (111) It is well established that the TiO atomic planes, and their ability to accommodate chemical doping by oxygen vacancies at the surface region, play a key role in the formation of the 2DEG at the surface of SrTiO 3 (001). Thus, as a step forward to understand the formation of 2DEGs in TMOs, it is natural to focus on pure TiO 2 crystals such as rutile or anatase. In fact, it is known that, for both rutile and anatase crystal sur...

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“…On the other hand, the debate over the purity of graphite and oxide substrates continues in parallel [35][36][37][38][39]. Pristine graphite and oxides substrates are often ferromagnetic due to different contaminations or due to intrinsic defects [36,[40][41][42], which hamper the interpretation of the observed ferromagnetism. Indeed, Nair et al…”

Section: Introductionmentioning

confidence: 99%

Defect-induced magnetism in SiC: Interplay between ferromagnetism and paramagnetism

et al. 2015

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Defect-induced ferromagnetism has triggered a lot of investigations and controversies. The major issue is that the induced ferromagnetic signal is so weak that it can sufficiently be accounted for by trace contamination. To resolve this issue, we studied the variation of the magnetic properties of SiC after neutron irradiation with fluence covering four orders of magnitude. A large paramagnetic component has been induced and scales up with defect concentration, which can be well accounted for by uncoupled divacancies. However, the ferromagnetic contribution is still weak and only appears in the low fluence range of neutrons or after annealing treatments. First-principles calculations hint towards a mutually exclusive role of the concentration of defects: a higher defectconcentration favors a larger magnetic interaction at the expense of spin polarization. Combining both experimental and first-principles calculation results, the defect-induced ferromagnetism can probably be understood as a local effect which cannot be scaled up with the volume. * Electronic address: s.zhou@hzdr.de 2

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Extrinsic origin of ferromagnetism in single crystalline LaAlO3 substrates and oxide films

Cited by 38 publications

References 10 publications

Defect-induced ferromagnetism in crystalline SrTiO3

Defect-induced ferromagnetism in crystalline SrTiO3

Engineering two-dimensional electron gases at the (001) and (101) surfaces ofTiO2anatase using light

Defect-induced magnetism in SiC: Interplay between ferromagnetism and paramagnetism

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