Solid State Physics Laboratory

About: Solid State Physics Laboratory is a facility organization based out in Delhi, India. It is known for research contribution in the topics: Quantum dot & Dielectric. The organization has 1754 authors who have published 2597 publications receiving 50601 citations.

Nano-iron pyrite seed dressing: a sustainable intervention to reduce fertilizer consumption in vegetable (beetroot, carrot), spice (fenugreek), fodder (alfalfa), and oilseed (mustard, sesamum) crops

Abstract: Continuous agricultural innovations are required to feed the exploding human population through natural or artificial resources. Though light is ample on earth, two-third of unavailable ocean and one-third of available soil are major limiting factors to free growth. Excessive fertilizer usage is irreversibly altering the chemical ecology of soil, further reducing the available area. Seed metabolism might be a potential answer to this resource crunch. Without genetic modification and thus maintaining the existing biodiversity, manipulation of seed metabolism at the very onset of germination is a sustainable alternative. The current work presents seed priming with iron pyrite (FeS2) prior to sowing as one such sustainable and innovative intervention to reduce fertilizer consumption in vegetable (beetroot, carrot), spice (fenugreek), fodder (alfalfa), and oilseed (mustard, sesamum) crops. A 12-h seed pretreatment in an aqueous suspension of nano-iron disulfide/pyrite (FeS2) resulted in significant yield increase in the above crops. While agriculturists aim to restore the natural genomic diversity of different domesticated crops, environmental engineers require technologies to reduce fertilizer consumption without compromising agricultural yields, thereby making the planet more sustainable. This nanoscale seed pretreatment approach using FeS2, otherwise a benign earth abundant mineral, suggests the sustainable opportunity to translate this technology to other crops thereby enhancing the global agricultural production.

Spin, charge, and bonding in transition metal mono-silicides

Abstract: We review some of the relevant physical properties of the transition metal mono-silicides with the FeSi structure (CrSi, MnSi, FeSi, CoSi, NiSi, etc.) and explore the relation between their structural characteristics and the electronic properties. We confirm the suggestion originally made by Pauling that the FeSi structure supports two quasi-atomic d-states at the transition metal atom. This shell contains from 0 to 4 electrons in the sequence CrSi to NiSi. In FeSi the two quasi-atomic d-electrons are responsible for the high temperature S = 1 state, which is compensated for T = 0 by two itinerant electrons associated with the FeSi resonance bonds.

Charge fluctuations and image potential at oxide-metal interfaces

Abstract: We analyze the dynamical response of the Ag metal surface to electronic excitations in a MgO(100)/Ag(100) oxide-metal interface system. Intrinsic and extrinsic surface plasmon excitations are discussed in relation to mutual interactions between the oxide and the metal. A direct relationship is established between the reduction of charge fluctuation energies in the MgO(100) layers and the image charge screening by the Ag(100) metal surface.

Aharonov-Bohm oscillations in the presence of strong spin-orbit interactions.

Abstract: Interference phenomena with particles have challenged physicists since the foundation of quantum mechanics. A charged particle traversing a ringlike mesoscopic structure in the presence of an external magnetic fluxacquires a quantum mechanical phase. The interference phenomenon based on this phase is known as the Aharonov-Bohm (AB) effect (1), and manifests itself in oscillations of the resist- ance of the mesoscopic ring with a period of � 0 h=e, where � 0 is the flux quantum. The Aharonov-Bohm phase was later recognized as a special case of the geometric phase (2,3) acquired by the orbital wave function of a charged particle encircling a magnetic flux line. The particle's spin can acquire an additional geometric phase in systems with spin-orbit interactions (SOI) (4 -6). The investigation of this spin-orbit (SO) induced phase in a solid-state environment is currently the subject of intensive experimental work (7-12). The common point of these experiments is the investigation of electronic transport in ringlike structures defined on two-dimensional (2D) semi- conducting systems with strong SOI. Electrons in InAs were investigated in a ring sample with time dependent fluctuations (7), as well as in a ring side coupled to a wire (9). An experiment on holes in GaAs (8) showed B-periodic oscillations with a relative amplitudeR=R < 10 3 . These observations (7,8) were analyzed with Fourier transforms and interpreted as a manifestation of Berry's phase. Further studies on electrons in a HgTe ring (10) and in an InGaAs ring network (11) were discussed in the framework of the Aharonov-Casher effect. In systems with strong SOI, an inhomogeneous, momen- tum dependent intrinsic magnetic field Bint, perpendicular to the particle's momentum, is present in the reference frame of the moving carrier (13). The total magnetic field seen by the carrier is therefore Btot Bext Bint, where Bext is the external magnetic field perpendicular to the 2D system and B int is the intrinsic magnetic field in the plane of the 2D system present in the moving reference frame (right inset Fig. 1(a)). The particle's spin precesses around Btot and accumulates an additional geometric phase upon cyclic evolution. Effects of the geometric phases are most prominently expressed in the adiabatic limit, when the precession fre- quency of the spin around the local field Btot is much faster than the orbital frequency of the charged particle carrying the spin (4). In this limit the ring can be considered to consist of two uncoupled types of carriers with opposite spins (14). The total accumulated phase, composed of the AB phase and the SO induced geometric phase, is different for the two spin species, � totABSO, and the mag- netoresistance of the ring is obtained as the superposition of the oscillatory contributions from the two spin species. Such a superposition is predicted to produce complex, beating-like magnetoresistance oscillations with nodes de- veloping at particular values of the external B field, where the oscillations from the two spin species have opposite phases (5). Both h=e and h=2e peaks in the Fourier spec- trum of the magnetoresistance oscillations are predicted to be split in the presence of strong SOI (5,15). The interpretation of the split Fourier signal in Ref. (7)