Herein, we predict that a 1D chain of Ti@C32-C 2-Ti@C32 (TEMF) will act as a spin switch in the presence of an electric field. The spin resolved density of states analyses reveal that, surprisingly, both the low- and high-spin states of TEMF are half-metal; however, the metallic density of states comes from the opposite spin channels of the two spin states. More remarkably, it is found that the electric field driven spin crossover between the low and high state in TEMF is achievable at field strength 1.04V/nm, which eventually leads to the realization of the first ever electrically operated spin switch device. © 2012 American Physical Society.

M CHATTOPADHYAYA

M M ALAM

S SEN

S CHAKRABARTI

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Physical Review Letters

We report on the potential use of Cr-Cn-Cr as a tunable molecular spin filter. Our study reveals that by suitably engineering the number of carbon atoms between the two Cr atoms, very strong spin filter efficiency could be achieved. An even-odd oscillation has been observed both in the spin polarized conductance as well as spin filter efficiency and it is reported that only with even number of carbon atoms the spin filter efficiency of the systems become 99.99%. Results obtained from the state-of-the-art nonequilibrium Green's function based calculations has been validated by analyzing the spin polarized transmission spectra, density of states, and molecular projected self consistent Hamiltonian states obtained at specific length of the carbon chain. The modification in singly occupied highest molecular orbital on going from odd to even number of carbon atoms explains the origin of the even-odd oscillation. © 2013 Elsevier B.V. All rights reserved.

Chemical Physics

In silico design of a tunable molecular spin filter using chromium-carbon-chromium chains

The generation of spin-based multi-qubit entangled states in the presence of an electric field is one of the most challenging tasks in current quantum-computing research. Such examples are still elusive. By using non-equilibrium Green′s function-based quantum-transport calculations in combination with non-collinear spin density functional theory, we report that an eight-spin-qubit entangled state can be generated with the high-spin state of a dinuclear Fe(II) complex when the system is placed in a molecular break junction. The possible gate operation scheme, gating time, and decoherence issues have been carefully addressed. Furthermore, our calculations reveal that the preservation of the high spin state of this complex is possible if the experimentalists keep the electric-field strength below 0.78 V-nm-1. In brief, the present study offers a unique way to realize the first example of a multi-qubit entangled state by electrical means only. Tale of entanglement: An eight-spin-qubit quantum entangled state can be realized in a dinuclear Fe(II) complex which (under a specific set of quantum-logic-gate operations) can act as a source of multi-qubit generation. The large decoherence time with high quantum fidelity factor makes the system an efficient quantum-computing object. © 2014 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

ChemPhysChem

Electrically controlled eight-spin-qubit entangled-state generation in a molecular break junction

We predict that the electric field induced spin-crossover in a double -NO2 substituted Fe(ii) complex will commence at the gate voltage, VG = -1.04 V and across this critical VG, the low and high spin states behave as "off" and "on" state, respectively which paves a unique way to realize an electronic spin switch controlled by a gate. © The Royal Society of Chemistry 2013.

RSC Advances

Chemical control of a molecular spin switch in the presence of a gate

Here, we predict that the ferromagnetically coupled cobalt-benzene-cobalt system will act as the smallest molecular spin filter with unprecedented spin injection coefficient. To validate our in-silico observation, we have performed state-of-the-art nonequilibrium Green's function calculations and analyzed the density of states of cobalt at the relativistic and nonrelativistic level of theory. Remarkably, we found that unpaired 3d electrons of cobalt are not participating in the spin transport process like other transition metal containing multidecker complexes. Instead, an admixture of the outer-sphere 4s and 4p orbitals of cobalt along with the 2p orbital of carbon of the benzene moiety is contributing to the singly occupied highest molecular orbital in the majority spin channel that creates a path for coherent spin transport leading to the extremely high spin injection coefficient of the system. The absence of the 3d electrons of cobalt in the spin transport process has been carefully examined, and it was found that the nodal structure of the 3d orbital of cobalt is not at all suitable for bonding in the cobalt-benzene-cobalt system. The whole study indicates that the underlying mechanism of the spin filter action in cobalt-benzene-cobalt is completely distinctive from the other known materials. © 2010 American Chemical Society.

Journal	Physical Review Letters
Publisher	AMER PHYSICAL SOC
ISSN	0031-9007