Antiferromagnetic Interactions in Single Crystalline<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Zn</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Co</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi mathvariant="normal">O</mml:mi></mml:math>Thin Films

Sati, Prakash Chandra; Deparis, C.; Morhain, C.; Schäfer, Steffen; Stepanov, A.

doi:10.1103/physrevlett.98.137204

Cited by 129 publications

(96 citation statements)

References 29 publications

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“…Within the LSDA+ U, both the in-plane and out-of-plane magnetic interactions are antiferromagnetic and their strength is more or less independent of the Co cluster size. From magnetic measurements, exchange parameters J in = −21 K and J out = −9 K were reported, 27 which are in good agreement with our LSDA+ U values, especially for the J in / J out ratio. A good consensus exists also with the the- 28 which reported the values of J in = −23 K and J out = −8 K for an isolated pair, with the LSDA+ U approach.…”

Section: A Structural and Magnetic Propertiessupporting

confidence: 74%

Microscopic picture of Co clustering in ZnO

et al. 2009

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Density functional theory was applied to study the chemical and magnetic interactions between Co atoms doped in ZnO. It was found that the Co impurities tend to form nanoclusters and the interactions between these atoms are antiferromagnetic within the local spin-density approximation ͑LSDA͒ + Hubbard U approach. The extracted interatomic exchange parameters agree reasonably well with recent experimental results. We have analyzed and compared the electronic structure obtained using the LSDA and LSDA+ U approaches and found that the LSDA+ U gives the most reasonable result, highlighting the importance of short-ranged antiferromagnetic interactions due to superexchange.

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Section: A Structural and Magnetic Propertiessupporting

confidence: 74%

Microscopic picture of Co clustering in ZnO

et al. 2009

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“…The Weiss temperature of all the samples are negative, consistent with the report of antiferromagnetic interaction in paramagnetic Zn 1−x Co x O thin films. 18 In order to see the effects of vacuum annealing on the electronic and magnetic properties of the Co ion, we have measured the Co 2p XMCD spectra of the P O2 =10 −2 Pa film after vacuum annealing, too. Figure 5͑a͒ shows the Co 2p 3/2 XAS and XMCD spectra of the P O2 =10 −2 Pa film before and after the annealing.…”

Section: Resultsmentioning

confidence: 99%

“…In the previous XMCD measurements on a heteroepitaxial Zn 1−x Co x O thin film grown on Al 2 O 3 ͑0001͒ substrates, 17 we have concluded that the ferromagnetism comes from Co ions substituting the Zn site in ZnO, and proposed that nonferromagnetic Co ions are strongly coupled antiferromagnetically with each other from the linear magnetic-field ͑H͒ dependence and temperature ͑T͒ independence of XMCD. Sati et al 18 reported antiferromagnetic interaction in single crystalline Zn 1−x Co x O thin films with low Co concentration ͑x = 0.003-0.005͒ from magnetic and EPR measurements. On the other hand, there are some reports that the Co 3d electrons are not the origins of the ferromagnetism 19 or that metallic Co atoms contribute to the ferromagnetism.…”

Section: Introductionmentioning

confidence: 99%

Antiferromagnetic interaction between paramagnetic Co ions in the diluted magnetic semiconductorZn1−xCoxO

et al. 2010

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The magnetic properties of Zn 1−x Co x O ͑x = 0.07 and 0.10͒ thin films, which were homoepitaxially grown on a ZnO͑0001͒ substrates with varying relatively high oxygen pressure, have been investigated using x-ray magnetic circular dichroism ͑XMCD͒ at Co 2p core-level absorption edge. The line shapes of the absorption spectra are the same in all the films and indicate that the Co 2+ ions substitute for the Zn sites. The magneticfield and temperature dependences of the XMCD intensity are consistent with the magnetization measurements, indicating that except for Co there are no additional sources for the magnetic moment, and demonstrate the coexistence of paramagnetic and ferromagnetic components in the homoepitaxial Zn 1−x Co x O thin films, in contrast to the ferromagnetism in the heteroepitaxial Zn 1−x Co x O films studied previously. The analysis of the XMCD intensities using the Curie-Weiss law reveals the presence of antiferromagnetic interaction between the paramagnetic Co ions. Missing XMCD intensities and magnetization signals indicate that most of Co ions are nonmagnetic probably because they are strongly coupled antiferromagnetically with each other. Annealing in a high vacuum reduces both the paramagnetic and ferromagnetic signals. We attribute the reductions to thermal diffusion and aggregation of Co ions with antiferromagnetic nanoclusters in Zn 1−x Co x O.

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“…23 Very recently, Iuşan et al 24 have shown that the magnetic exchange parameters calculated with LSDA+ U for Co doped ZnO are in good agreement with the magnetic measurements. 25 Considering the importance of Coulomb correlation, we have employed GGA+ U method for the description of TM-d states in the TM doped ZnO cluster. We have calculated the stability of the cluster on doping, the corresponding magnetic moments, and magnetic interactions between two TM ions.…”

Section: Resultsmentioning

confidence: 99%

Electronic structure and magnetism of transition metal doped Zn12O12 clusters: Role of defects

Ganguli

Dasgupta

Sanyal

2010

Journal of Applied Physics

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Impacts of enhanced electronic correlation in anion p-orbitals on electronic structure and magnetic properties of nitrogen or carbon doped zinc oxide J. Appl. Phys. 111, 07E313 (2012) Magneto-optical spectrum of ZnO nanorods J. Appl. Phys. 111, 044305 (2012) First-principles study on electronic structures and magnetic properties of AlN nanosheets and nanoribbons J. Appl. Phys. 111, 043702 (2012) p-f hybridization in the ferromagnetic semiconductor HoN Appl. Phys. Lett. 100, 072108 (2012) Visible light photocatalysis of single-walled (Zn4/6Cu2/6O)3/(Zn5/6Cu1/6O)3 superlattice nanotube for redox reaction of water calculated by generalized gradient approximations with the Hubbard U model J. Appl. Phys. 111, 034318 (2012) Additional information on J. Appl. Phys. We present a comprehensive study of the energetics and magnetic properties of ZnO clusters doped with 3d transition metals ͑TMs͒ using ab initio density functional calculations in the framework of generalized gradient approximation+ Hubbard U ͑GGA+ U͒ method. Our results within GGA+ U for all 3d dopants except Ti indicate that antiferromagnetic interaction dominates in a neutral, defect-free cluster. Formation energies are calculated to identify the stable defects in the ZnO cluster. We have analyzed in details the role of these defects to stabilize ferromagnetism when the cluster is doped with Mn, Fe, and Co. Our calculations reveal that in the presence of charged defects the TM atoms residing at the surface of the cluster may have an unusual oxidation state, that plays an important role to render the cluster ferromagnetic. Defect induced magnetism in ZnO clusters without any TM dopants is also analyzed. These results on ZnO clusters may have significant contributions in the nanoengineering of defects to achieve desired ferromagnetic properties for spintronic applications.

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Antiferromagnetic Interactions in Single CrystallineZn1−xCoxOThin Films

Cited by 129 publications

References 29 publications

Microscopic picture of Co clustering in ZnO

Microscopic picture of Co clustering in ZnO

Antiferromagnetic interaction between paramagnetic Co ions in the diluted magnetic semiconductorZn1−xCoxO

Electronic structure and magnetism of transition metal doped Zn12O12 clusters: Role of defects

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