Incoherent effect of Fe and Ni substitutions in the ferromagnetic-insulator La0.6Bi0.4MnO3+δ
Asish K. KunduMd. Motin SeikhAkhilesh K. SrivastavaShivam MahajanRatnamala ChatterjeeV. PralongB. Raveau
8
Citation
24
Reference
10
Related Paper
Citation Trend
Abstract:
A comparative study of the effect of Fe and Ni doping on the bismuth based perovskite La0.6Bi0.4MnO3.1, a projected spintronics magnetic semiconductor has been carried out. The doped systems show an expressive change in magnetic ordering temperature. However, the shifts in ferromagnetic transition (TC) of these doped phases are in opposite direction with respect to the parent phase TC of 115 K. The Ni-doped phase shows an increase in TC ∼200 K, whereas the Fe-doped phase exhibits a downward shift to TC∼95 K. Moreover, the Fe-doped is hard-type whereas the Ni-doped compound is soft-type ferromagnet. It is observed that the materials are semiconducting in the ferromagnetic phase with activation energies of 77 & 82 meV for Fe & Ni-doped phases, respectively. In the presence of external magnetic field of 7 T, they exhibit minor changes in the resistivity behaviors and the maximum isothermal magnetoresistance is around −20% at 125 K for the Ni-phase. The results are explained on the basis of electronic phase separation and competing ferromagnetic and antiferromagnetic interactions between the various mixed valence cations.Keywords:
Magnetic semiconductor
Metal–insulator transition
Semiconductor spintronics has now reached a stage where the basic physical mechanisms controlling spin injection and detection are understood. Moreover, some critical technological issues involved in the growth and lithography of the magnetic semiconductors have been solved. This has allowed us to explore the physics of spintronic nanostructures. In this talk I will give examples of devices we have fabricated using two different classes of dilute magnetic semiconductors (DMSs). In II-VI semiconductors, magnetic impurities can be introduced iso-electronicallly, allowing n-and p-type doping of the material. Moreover, the layers can be grown by molecular beam epitaxy (MBE) at relatively high temperatures, so that the carrier mean free path is relatively long and devices may be constructed that rely on the typical properties of compound semiconductors, such as e.g. easily accessible confinement states. The drawback of magnetic II-VI's is, of course, that the materials are not ferromagnets, but are paramagnets with a very high effective g-factor. Dilute magnetic III-V semiconductors are ferromagnetic. This is because the magnetic impurities now act as acceptors, and the resulting compound have large hole concentrations. The holes then intermediate in the ferromagnetic alignment of the impurities. The problem with II-V DMSs is that sizable concentrations of the magnetic impurities can only be incorporated using low-temperature MBE, which implies relatively low sample quality, and very short carrier mean free path. This implies that the devices one can construct our of such compounds are much more like the devices already known from metallic spintronics. Here, we will briefly discuss the type of devices one can fabricate from these materials.
Magnetic semiconductor
Cite
Citations (2)
Diluted magnetic semiconductors (DMS), in which transition metal (TM) ions primarily substitute cations of the host material form a class of spintronic materials. They exhibit ferromagnetism(FM) and half metallicity. Knowledge of magnetic interactions is crucial for obtaining room temperature ferromagnetism in a DMS. II-VI and III-V semiconductors are proving to be advantageous owing to their wide band gap, electric and piezoelectric properties and find a wide range of applications in optoelectronics, power electronics and spintronics [1]–[5].
Magnetic semiconductor
Wide-bandgap semiconductor
Cite
Citations (0)
Antiferromagnetic spintronics exploits unique properties of antiferromagnetic materials to create new and improved functionalities in future spintronic applications. Here, we briefly review the experimental efforts in our group to unravel spin transport properties in antiferromagnetic materials. Our investigations were initially focused on metallic antiferromagnets, where the first evidence of antiferromagnetic spin-transfer torque was discovered. Because of the lack of metallic antiferromagnets, we then shifted towards antiferromagnetic Mott insulators, where a plethora of transport phenomena was found. For instance, we observed a very large anisotropic magnetoresistance, which can be used to detect the magnetic state of an antiferromagnet. We also observed reversible resistive switching and now provide unequivocal evidence that the resistive switching is associated with structural distortions driven by an electric field. Our findings support the potential of electrically controlled functional oxides for various memory technologies.
Cite
Citations (2)
Semiconductor spintronics has now reached a stage where the basic physical mechanisms controlling spin injection and detection are understood. Moreover, some critical technological issues involved in the growth and lithography of the magnetic semiconductors have been solved. This has allowed us to explore the physics of spintronic nanostructures. In this talk I will give examples of devices we have fabricated using two different classes of dilute magnetic semiconductors (DMSs). In II-VI semiconductors, magnetic impurities can be introduced iso-electronicallly, allowing n-and p-type doping of the material. Moreover, the layers can be grown by molecular beam epitaxy (MBE) at relatively high temperatures, so that the carrier mean free path is relatively long and devices may be constructed that rely on the typical properties of compound semiconductors, such as e.g. easily accessible confinement states. The drawback of magnetic II-VI's is, of course, that the materials are not ferromagnets, but are paramagnets with a very high effective g-factor. Dilute magnetic III-V semiconductors are ferromagnetic. This is because the magnetic impurities now act as acceptors, and the resulting compound have large hole concentrations. The holes then intermediate in the ferromagnetic alignment of the impurities. The problem with II-V DMSs is that sizable concentrations of the magnetic impurities can only be incorporated using low-temperature MBE, which implies relatively low sample quality, and very short carrier mean free path. This implies that the devices one can construct our of such compounds are much more like the devices already known from metallic spintronics. Here, we will briefly discuss the type of devices one can fabricate from these materials.
Magnetic semiconductor
Cite
Citations (0)
Antiferromagnetic materials are promising for future spintronic applications owing to their intrinsic appealing properties like zero stray field and ultrafast dynamics. In the past decade, a lot of research has been devoted to unraveling spin transport properties in antiferromagnetic materials. It has been realized that antiferromagnets have more to offer than just being used as passive components in exchange bias applications. Especially, the recent demonstrations of electrical manipulation and detection of antiferromagnetic spins opens a new chapter in the story of spintronics. This paradigm shift provides possibilities for radically new concepts for spin control in electronics. Here, we firstly introduce the antiferromagnetic materials suitable for antiferromagnetic spintronics and their fundamental properties. Then the manipulations of antiferromagnetic states including magnetic, strain, optical, and electrical methods, and the intrinsic origins of different antiferromagnets are presented. Finally, we focus on the topological antiferromagnetic spintronics that is exploring the links between antiferromagnetic spintronics and topological structures in real and momentum space.
Cite
Citations (2)
Cite
Citations (265)
The co-precipitation approach was utilized to experimentally synthesize ZnO, Zn0.96Gd0.04O and Zn0.96-x Gd0.04Co x O (Co = 0, 0.01, 0.03, 0.04) diluted magnetic semiconductor nanotubes. The influence of gadolinium and cobalt doping on the microstructure, morphology, and optical characteristics of ZnO was investigated, and the Gd doping and Co co-doping of the host ZnO was verified by XRD and EDX. The structural investigation revealed that the addition of gadolinium and cobalt to ZnO reduced crystallinity while maintaining the preferred orientation. The SEM study uncovered that the gadolinium and cobalt dopants did not affect the morphology of the produced nanotubes, which is further confirmed through TEM. In the UV-vis spectra, no defect-related absorption peaks were found. By raising the co-doping content, the crystalline phase of the doped samples was enhanced. It was discovered that the dielectric response and the a.c. electrical conductivity display a significant dependent relationship. With the decreasing frequency and increasing Co co-dopant concentration, the εr and ε'' values decreased. It was also discovered that the εr, ε'', and a.c. electrical conductivity increased when doping was present. Above room temperature, co-doped ZnO nanotubes exhibited ferromagnetic properties. The ferromagnetic behaviour increased as Gd (0.03) doping increased. Increasing the Co content decreased the ferromagnetic behaviour. It was observed that Zn0.96-x Gd0.04Co x O (x = 0.03) nanotubes exhibit superior electrical conductivity, magnetic and dielectric characteristics compared to pure ZnO. This high ferromagnetism is typically a result of a magnetic semiconductor that has been diluted. In addition, these nanoparticles are utilized to design spintronic-based applications in the form of thin-films.
Magnetic semiconductor
Cite
Citations (19)
In the past five years, most of the paradigmatic concepts employed in spintronics have been replicated substituting ferromagnets by antiferromagnets in the critical parts of the devices. The numerous research efforts directed to manipulate and probe the magnetic moments in antiferromagnets have been gradually established a new and independent field known as antiferromagnetic spintronics. In this paper, we focus on the electrical control and detection of antiferromagnetic moments at a constant temperature. We address separately the experimental results concerning insulating and metallic thin films as they correspond to voltage and electrical current controlled devices, respectively. First, we present results on the voltage control of antiferromagnetic order in insulating thin films. The experiments show that voltage pulses can switch the chirality of a modulated antiferromagnetic structure. Second, we describe the recent advances in metallic antiferromagnetic systems. We present results obtained with the first USB-operated portable device able to perform the nonvolatile electrical current-induced switching of an antiferromagnet combined with magnetoresistive readout at room temperature. We discuss on potential applications that can be realized using antiferromagnetic memory cells.
Cite
Citations (5)
Magnetic semiconductor
Cite
Citations (29)
Diluted magnetic semiconductors could be used to construct magnetic and electronic device that utilize simultaneously the spin and charge degrees of freedom of carrier. Recent research on ferromagnetic semiconductors has stimulates the development of spintronics. The fabrication of room-temperature ferromagnetic semiconductors, high-efficiency spin injection, and spin manipulation and transport in semiconductors have attracted considerable interest in the past few years. Diluted magnetic semiconductors exhibit strong spin-dependent optical and transport properties, and these effects provide a physical basis for semiconductor spintronics devices.
Magnetic semiconductor
Spin pumping
Spinplasmonics
Charge carrier
Cite
Citations (0)