Magnetoresistance of epitaxial GdN films

Maity, T.; Trodahl, Joe; Granville, S.; Vézian, S.; Natali, F.; Ruck, B. J.

doi:10.1063/5.0022950

Cited by 5 publications

(3 citation statements)

References 25 publications

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“…Even if the strength of the external magnetic field is not enough to generate a complete magnetic ordering, slight modifications in the microscopic structure of the barrier arise [55], which has been already predicted to occurr in systems with tunable domain walls [56], intrinsic SOC [57] and magnetic impurities [58]. At zero field, the magnetic disorder is maximum and likely introduces electronic defect states in the barrier [59]. As the field increases, the system undergoes towards a more ordered phase, and hence defect states density reduces.…”

Section: Resultsmentioning

confidence: 96%

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

Ahmad,

Minutillo,

Capecelatro

et al. 2021

Preprint

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Section: Resultsmentioning

confidence: 96%

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

Ahmad,

Minutillo,

Capecelatro

et al. 2021

Preprint

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“…Even if the strength of the external magnetic field is not enough to generate a complete magnetic ordering, slight modifications in the microscopic structure of the barrier arise 62 , which has been already predicted to occur in systems with tunable domain walls 63 , intrinsic SOC 64 , and magnetic impurities 65 . At zero field, the magnetic disorder is maximum and likely introduces electronic defect states in the barrier 66 . As the field increases, the system undergoes toward a more ordered phase, and hence defect states density reduces.…”

Section: Resultsmentioning

confidence: 99%

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

et al. 2022

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The increased capabilities of coupling more and more materials through functional interfaces are paving the way to a series of exciting experiments and extremely advanced devices. Here we focus on the capability of magnetically inhomogeneous superconductor/ferromagnet (S/F) interfaces to generate spin-polarized triplet pairs. We build on previous achievements on spin-filter ferromagnetic Josephson junctions (JJs) and find direct correspondence between neat experimental benchmarks in the temperature behavior of the critical current and theoretical modelling based on microscopic calculations, which allow to determine a posteriori spin-singlet and triplet correlation functions. This kind of combined analysis provides an accurate proof of the coexistence and tunability of singlet and triplet transport. This turns to be a powerful way to model disorder and spin-mixing effects in a JJ to enlarge the space of parameters, which regulate the phenomenology of the Josephson effect and could be applied to a variety of hybrid JJs.

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“…The scattering that provides the resistance then must scatter electrons from states on the surface to other states that are essentially on the surface, and so the maximum amount of scattering will occur when the length scale associated with the magnetic disorder scattering vector corresponds to the size of the Fermi surface. This mechanism is discussed in detail for GdN in Maity et al [127] where it is attributed as the dominant contribution to the sample magnetoresistance.…”

Section: Temperature-dependent Measurementsmentioning

confidence: 95%

Rare-earth nitride solid solutions

Miller¹

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Improvements to computing efficiency are required to offset the energy costs of increasing demand on cloud computing data centres (the cost of which is currently borne by fossil fuel energy production, and thus, the environment) [4]. The 20th-century technologies that currently support our heavy use of computers are unable to keep providing efficiency improvements due to the fundamental limits associated with the physics that they rely on to operate, meaning that new physical mechanisms are required [5–8]. Improvements to computing efficiency are offered by superconducting computing, but the implementation of this technology requires cryogenically-viable memory, which is not currently available [9, 10]. The research field of spintronics promises devices with plausible improvements over current memory technologies, but these devices require materials in which complex properties can be controlled [11, 12]. The rare-earth nitrides are a series of intrinsic ferromagnetic semiconductors, that have been included in device architectures with some success [13–15]. Their combination in a solid solution offers control over the magnetic and electrical properties of a homogenous single-layer thin film, allowing the fine-tuning of the properties to meet the requirements of application. Understanding the material properties of rare-earth nitride solid solutions is the central topic of this thesis. This thesis documents research into the properties of Gdx Sm1−x N, a solid solution of the rare-earth nitrides GdN and SmN. We present magnetometry, x-ray magnetic circular dichroism (XMCD), and Hall effect measurements on a series of GdxSm1−xN films. Magnetometry results show a linear dependence of the saturation magnetisation on the Gd fraction of the films, x, over much of the range 0 ≤ x ≤ 1. Further results show that GdxSm1−xN films with a low Gd fraction (x ≤ 0.3) exhibit perpendicular magnetic anisotropy. Films for which x ≤ 0.2 show a deviation from the linear dependence of the saturation magnetisation on x, and extremely low magnetic moments. This low moment results, in part, from the opposition of the net moment of the Gd3+ and Sm3+ ions. The opposition of the net moment comes from the orbital-dominant magnetism of the Sm3+ ion and the alignment of the Gd3+ and Sm3+ spins by the exchange interaction (which is confirmed by XMCD). This combination of the orbital-dominant magnetism of the Sm3+ ion and the alignment of the Gd3+ and Sm3+ spins by the exchange interaction also causes there to be compositions of GdxSm1−xN for which the net magnetic moment or the net angular momentum of the solution is zero. These “compensation points” are familiar from other classes of material generally held to be promising for similar applications [16, 17]. Measurements of XMCD show an increasing spin polarisation of Sm3+ as a function of x, changing where one expects to find the angular momentum compensation point xa. The value of xa is estimated with reference to the XMCD measurements to be xa = 0.245. Furthermore, measurements of the anomalous Hall effect are used to locate the compensation point of the net magnetic moment, xc , which is found to be xc = 0.05.

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Magnetoresistance of epitaxial GdN films

Cited by 5 publications

References 25 publications

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

Coexistence and tuning of spin-singlet and triplet transport in spin-filter Josephson junctions

Rare-earth nitride solid solutions

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