Bound magnetic polaron interactions in insulating doped diluted magnetic semiconductors

Durst, Adam C.; Bhatt, R. N.; Wolff, Peter

doi:10.1103/physrevb.65.235205

Cited by 256 publications

(147 citation statements)

References 28 publications

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“…21,32,36 Again with the lowering of temperature both polaron size and total intrapolaron exchange energy increase logarithmically and probability of overlapping of BMPs and interactions between BMPs increases, which leads to the prominent long range FM ordering in the sample at low temperature. 34,37 Compared to other previously reported work on doped Gd 2 18 exhibits paramagnetic nature with maximum magnetization at 300 K around 5.7 emu/g with a maximum applied field of $ 5 T. Hazarika et al 39 reported the superparamagnetic behavior of Gd 2 O 3 nanorod at 300 K with maximum magnetization $ 6 emu/g at 6 T. Patel et al 32 reported that the paramagnetic behavior with feeble antiferromagnetic contribution in Co doped Gd 2 O 3 nanorod with maximum magnetization at 300 K was $ 0.06 emu/g with a maximum applied field of $ 2 T. But in the present system, we have investigated the magnetic properties of Ni doped Gd 2 O 3 (Gd 1.90 Ni 0.10 O 3Àd ), where room temperature ferromagnetism is observed in the low field region ($ 4000 Oe), but with maximum applied field of $ 5 T dominant paramagnetic behavior with maximum magnetization at 300 K is $ 5.8 emu/g is found. The formation of oxygen vacancy to maintain charge neutrality in GNO plays a key role for the enhancement of magnetization compared to Co and Fe doped Gd 2 O 3 .…”

Section: Magnetic Propertiesmentioning

confidence: 99%

“…The magnetic behavior of doped diluted magnetic semiconductors is characterized by the interaction between large collective spins which are known as bound magnetic polarons (BMPs). 34 According to the Hund's rule and Pauli Exclusion Principle, spin orientations of the trapped electrons and the neighbouring Ni ions should be parallel in order to achieve ferromagnetic ordering. 35 Moreover, the doping of Ni 2+ ions may enhance the number of oxygen vacancies in doped Gd 2 O 3 to maintain charge neutrality in the system.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

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Microstructural Investigation, Raman and Magnetic Studies on Chemically Synthesized Nanocrystalline Ni-Doped Gadolinium Oxide (Gd1.90Ni0.10O3−δ)

Sarkar

Mandal

Dalal

et al. 2018

Journal of Elec Materi

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Nanocrystalline Ni-doped gadolinium oxide (Gd 1.90 Ni 0.10 O 3Àd , GNO) is synthesized by co-precipitation method. The as-prepared sample is annealed in vacuum at 700°C for 6 h. Analyses of the x-ray diffractogram by Rietveld refinement method, transmission electron microscopy and Raman spectroscopy of GNO recorded at room temperature confirmed the pure crystallographic phase and complete substitution of Ni-ions in Gd 2 O 3 lattice. Magnetization (M) as a function of temperature (T) and magnetic field (H) is measured by a superconducting quantum interference device magnetometer, which suggests the presence of ferromagnetic/antiferromagnetic phases together with a paramagnetic phase. From the M-T curve it can be shown that the ferromagnetic phase dominates over para-/antiferromagnetic phases in the temperature range of 300-100 K, but from 100 K to 50 K, the antiferromagnetic phase dominates over ferro-/paramagnetic phases. Hysteresis loops recorded at different temperatures indicate the presence of weak ferro-/antiferromagnetism, which dominates in the low field region ($ 4000 Oe), above which magnetization increases linearly. The sharp increase of magnetization in M-T curve observed in the temperature range of 50-5 K confirms the presence of dominating ferromagnetic plus paramagnetic phase over antiferromagnetic part. For the first time a combined formula generated from threedimensional (3D) spin wave model and Johnston formula is proposed to analyze the coexistence of different magnetic phases in different temperature ranges. Interestingly, the combined formula successfully explains the co-existence of different magnetic phases along with their contribution at different temperatures. The onset of ferromagnetism in Gd 1.90 Ni 0.10 O 3Àd is explained by oxygen vacancy mediated F-centre exchange (FCE) coupling mechanism.

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Section: Magnetic Propertiesmentioning

confidence: 99%

Section: Magnetic Propertiesmentioning

confidence: 99%

Microstructural Investigation, Raman and Magnetic Studies on Chemically Synthesized Nanocrystalline Ni-Doped Gadolinium Oxide (Gd1.90Ni0.10O3−δ)

Sarkar

Mandal

Dalal

et al. 2018

Journal of Elec Materi

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“…Whether this exchange coupling is ferromagnetic or antiferromagnetic is still subject to debate. [32][33][34] A Kondo-lattice model containing the impurity orbitals and their hybridization with the conduction band was also formulated for this topic. 35 According to Arnold and Kroha, 29 the existence of preformed local moments at the impurity levels inside the semiconducting gap is essential to explain the distinct double-dome shape of the magnetization M(T), although it has become apparent from numerous experiments that oxygen deficiency alone, without doping localized moments, can be responsible for the unique double-dome feature.…”

Section: Introductionmentioning

confidence: 99%

Antiferromagnetic coupling in EuO1−x

2012

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The mechanism for the ferromagnetic order in oxygen-deficient europium monoxide EuO 1-x at temperatures higher than 69 K (the Curie temperature Tc of stoichiometric EuO) remains controversial. We have investigated the magnetization of EuO 1-x thin films prepared via pulsed laser deposition as a function of temperature and applied field. The ferromagnetic ordering above 69 K originates from the exchange coupling between the doped electrons and Eu 4f moments and is described using a magnetic polaron model. Our data show that the magnetic polarons are coupled antiferromagnetically to the Eu 4f local moments that dominate the magnetization below 69 K. The magnetic polaron state is stable below 69 K and seems to persist down to a relatively low temperature. An explanation is given to account for the antiferromagnetic coupling. We also describe the evolution of the phases of the magnetic orders as the temperature is varied in EuO 1-x .2

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“…11 The microstructural analysis does not show the formation of magnetic clusters such as Co-oxides and metallic Co (Supporting Information Figure S1). Moreover, CoO is an antiferromagnetic material, whose Néel temperature is 293 K. 14 …”

mentioning

confidence: 99%

Enhancement of magnetic properties in (Ga,Mn)N nanowires due to N2 plasma treatment

Baik

Shon

Kang

et al. 2006

Applied Physics Letters

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Ferromagnetic semiconductors with a high Curie temperature (>300 K) are believed to be suitable for future spintronics devices such as spin-light emitting diodes, spin-field effect transistors, and quantum computers. 1,2 The advantages of these devices include increased processing speed, lower power consumption, and higher information density, compared with conventional devices. 2 The recent recovery of organic semiconductors with magnetically aligned spins is also interesting because they can be synthesized under much less stringent conditions than inorganic semiconductors due to the low-temperature processing and mechanical flexibility. In particular, π-conjugated organic semiconductors such as 8-hydroxy-quinoline aluminum (Alq 3 , inset of Figure 1a) may be very good for transport of spin-polarized carriers because of the long spin diffusion length and giant magnetoresistance. 3 However, the spin injection efficiency was too low to be used in spin devices and the operation temperature was below 300 K, which might be attributed to the formation of insulating complexes at the interface of metal/Alq 3 (i.e., the interface roughness increased, causing suppression of spin injection to Alq 3 layer) and the conductivity mismatch. 4 Here we address this low spin injection efficiency issue for Alq 3 and suggest a solution. First let us note that both problems may be simultaneously solved by using organic-based magnets. Tetracyanoethylene-based organic magnets, for example, have been reported to be ferromagnetic at low and even at room temperatures. 5 Thus we attempted to modify Alq 3 itself and make it magnetic; Alq 3 -based magnets, if they possess ferromagnetism at room temperature, would be an ideal spin injection layer to an original semiconductor Alq 3 .A glass coating with 150 nm of indium-tin oxide (ITO) was used as the starting substrate. The ITO samples (after a general cleaning process) were loaded into a thermal evaporator at 1.0 × 10 -6 Torr, on which Co-doped Alq 3 layers with a thickness of 100 nm were coevaporated of pure Co metal (99.99%) and Alq 3 powders at room temperature. The Co concentrations in Alq 3 were determined to be 5% (Co/Al atomic ratio ) 0.5) and 10% (1) using the thickness ratio of Co and Alq 3 . Ni-doped Alq 3 was also prepared by the same method. For the measurement of magnetic properties, a Ag layer was deposited on the organic layers, playing a role in protecting the organic layers from moisture. Magnetization measurement was carried out using a superconducting quantum interference device magnetometer (MPMSXL, Quantum Design Co., Ltd.). We also employed a variety of measurement techniques utilizing synchrotron radiation, including X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD) to elucidate the origin of the ferromagnetism in the compound. Figure 1a shows the magnetic curves for the 5% Co-doped Alq 3 at 10 and 300 K. The hysteresis loop of the sample at 10 K showed clear ferromagnetic behavior with a coercive field of 170 Oe and a magnetic momen...

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Bound magnetic polaron interactions in insulating doped diluted magnetic semiconductors

Cited by 256 publications

References 28 publications

Microstructural Investigation, Raman and Magnetic Studies on Chemically Synthesized Nanocrystalline Ni-Doped Gadolinium Oxide (Gd1.90Ni0.10O3−δ)

Microstructural Investigation, Raman and Magnetic Studies on Chemically Synthesized Nanocrystalline Ni-Doped Gadolinium Oxide (Gd1.90Ni0.10O3−δ)

Antiferromagnetic coupling in EuO1−x

Enhancement of magnetic properties in (Ga,Mn)N nanowires due to N2 plasma treatment

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