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Quantum Advantage in a Molecular Spintronic Engine that Harvests Thermal Fluctuation Energy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2206688. [PMID: 36177716 DOI: 10.1002/adma.202206688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/25/2022] [Indexed: 06/16/2023]
Abstract
Recent theory and experiments have showcased how to harness quantum mechanics to assemble heat/information engines with efficiencies that surpass the classical Carnot limit. So far, this has required atomic engines that are driven by cumbersome external electromagnetic sources. Here, using molecular spintronics, an implementation that is both electronic and autonomous is proposed. The spintronic quantum engine heuristically deploys several known quantum assets by having a chain of spin qubits formed by the paramagnetic Co center of phthalocyanine (Pc) molecules electronically interact with electron-spin-selecting Fe/C60 interfaces. Density functional calculations reveal that transport fluctuations across the interface can stabilize spin coherence on the Co paramagnetic centers, which host spin flip processes. Across vertical molecular nanodevices, enduring dc current generation, output power above room temperature, two quantum thermodynamical signatures of the engine's processes, and a record 89% spin polarization of current across the Fe/C60 interface are measured. It is crucially this electron spin selection that forces, through demonic feedback and control, charge current to flow against the built-in potential barrier. Further research into spintronic quantum engines, insight into the quantum information processes within spintronic technologies, and retooling the spintronic-based information technology chain, can help accelerate the transition to clean energy.
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In Situ Pseudopotentials for Electronic Structure Theory. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:15103-15111. [PMID: 34295450 PMCID: PMC8287559 DOI: 10.1021/acs.jpcc.1c04791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Indexed: 06/13/2023]
Abstract
We present a general method of constructing in situ pseodopotentials from first-principles, all-electron, and full-potential electronic structure calculations of a solid. The method is applied to bcc Na, at low-temperature equilibrium volume. The essential steps of the method involve (i) calculating an all-electron Kohn-Sham eigenstate, (ii) replacing the oscillating part of the wave function (inside the muffin-tin spheres) of this state, with a smooth function, (iii) representing the smooth wave function in a Fourier series, and (iv) inverting the Kohn-Sham equation, to extract the pseudopotential that produces the state generated in steps i-iii. It is shown that an in situ pseudopotential can reproduce an all-electron full-potential eigenvalue up to the sixth significant digit. A comparison of the all-electron theory, in situ pseudopotential theory, and the standard nonlocal pseudopotential theory demonstrates good agreement, e.g., in the energy dispersion of the 3s band state of bcc Na.
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High Spin Polarization at Ferromagnetic Metal-Organic Interfaces: A Generic Property. J Phys Chem Lett 2016; 7:2310-2315. [PMID: 27266579 DOI: 10.1021/acs.jpclett.6b01112] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A high spin polarization of states around the Fermi level, EF, at room temperature has been measured in the past at the interface between a few molecular candidates and the ferromagnetic metal Co. Is this promising property for spintronics limited to these candidates? Previous reports suggested that certain conditions, such as strong ferromagnetism, i.e., a fully occupied spin-up d band of the ferromagnet, or the presence of π bonds on the molecule, i.e., molecular conjugation, needed to be met. What rules govern the presence of this property? We have performed spin-resolved photoemission spectroscopy measurements on a variety of such interfaces. We find that this property is robust against changes to the molecule and ferromagnetic metal's electronic properties, including the aforementioned conditions. This affirms the generality of highly spin-polarized states at the interface between a ferromagnetic metal and a molecule and augurs bright prospects toward integrating these interfaces within organic spintronic devices.
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Abstract
The properties of Fe(1,10-phenanthroline)2(NCS)2 (Fe-phen) molecules deposited on Co/Cu(111) are studied with scanning tunneling microscopy (STM) operated in ultrahigh vacuum at low temperature (4 K) and ab initio calculations. Both the experimental and theoretical results are used to identify the high-spin (HS) state of Fe-phen. Additionally, the calculations reveal a strong spin-polarization of the density of states (DOS) and is validated experimentally using the spin sensitivity of spin-polarized STM. Finally, it is shown that the magnetic moment of the Fe-ion within HS Fe-phen is strongly magnetically coupled to the underlying magnetic Co through the NCS groups. These findings enable promising spintronic perspectives.
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Spin-Dependent Hybridization between Molecule and Metal at Room Temperature through Interlayer Exchange Coupling. NANO LETTERS 2015; 15:7921-7926. [PMID: 26575946 DOI: 10.1021/acs.nanolett.5b02961] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We experimentally and theoretically show that the magnetic coupling at room temperature between paramagnetic Mn within manganese phthalocyanine molecules and a Co layer persists when separated by a Cu spacer. The molecule's magnetization amplitude and direction can be tuned by varying the Cu-spacer thickness and evolves according to an interlayer exchange coupling mechanism. Ab initio calculations predict a highly spin-polarized density of states at the Fermi level of this metal-molecule interface, thereby strengthening prospective spintronics applications.
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Exchange bias and room-temperature magnetic order in molecular layers. NATURE MATERIALS 2015; 14:981-984. [PMID: 26191660 DOI: 10.1038/nmat4361] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 06/22/2015] [Indexed: 06/04/2023]
Abstract
Molecular semiconductors may exhibit antiferromagnetic correlations well below room temperature. Although inorganic antiferromagnetic layers may exchange bias single-molecule magnets, the reciprocal effect of an antiferromagnetic molecular layer magnetically pinning an inorganic ferromagnetic layer through exchange bias has so far not been observed. We report on the magnetic interplay, extending beyond the interface, between a cobalt ferromagnetic layer and a paramagnetic organic manganese phthalocyanine (MnPc) layer. These ferromagnetic/organic interfaces are called spinterfaces because spin polarization arises on them. The robust magnetism of the Co/MnPc spinterface stabilizes antiferromagnetic ordering at room temperature within subsequent MnPc monolayers away from the interface. The inferred magnetic coupling strength is much larger than that found in similar bulk, thin or ultrathin systems. In addition, at lower temperature, the antiferromagnetic MnPc layer induces an exchange bias on the Co film, which is magnetically pinned. These findings create new routes towards designing organic spintronic devices.
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Ultimate limit of electron-spin precession upon reflection in ferromagnetic films. PHYSICAL REVIEW LETTERS 2011; 107:087203. [PMID: 21929201 DOI: 10.1103/physrevlett.107.087203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Indexed: 05/31/2023]
Abstract
We report the discovery of 180° electron-spin precession in spin-polarized electron-reflection experiments on Fe films on Ag(001), the largest possible precession angle in a single electron reflection. Both experiments as a function of Fe film thickness and ab initio calculations show that the appearance of this ultimate spin precession depends with utmost sensitivity on the relaxation of the Fe surface layers during growth. Similar spin precession is also predicted for other ferromagnetic films.
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Impact on interface spin polarization of molecular bonding to metallic surfaces. PHYSICAL REVIEW LETTERS 2010; 105:077201. [PMID: 20868071 DOI: 10.1103/physrevlett.105.077201] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Indexed: 05/29/2023]
Abstract
We have studied the repercussion of the molecular adsorption mechanism on the electronic properties of the interface between model nonmagnetic or magnetic metallic surfaces and metallo-organic phthalocyanines molecules (Pcs). Our intertwined x-ray absorption spectroscopy experiments and computational studies reveal that manganese Pc (MnPc) is physisorbed onto a Cu(001) surface and retains the electronic properties of a free molecule. On the other hand, MnPc is chemisorbed onto Co(001), leading to a dominant direct exchange interaction between the Mn molecular site and the Co substrate. By promoting an interfacial spin-polarized conduction state on the molecule, these interactions reveal an important lever to tailor the spintronic properties of hybrid organic-metallic interfaces.
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Electron spin precession upon reflecting from ferromagnetic surfaces. PHYSICAL REVIEW LETTERS 2006; 96:137206. [PMID: 16712030 DOI: 10.1103/physrevlett.96.137206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Indexed: 05/09/2023]
Abstract
Electrons with the polarization vector perpendicular to the magnetization of Fe, Co, and Ni films are spin analyzed after reflecting from the ferromagnet. At low primary electron energies a strong spin motion is found, namely, a precession of the polarization around the magnetization and a change of the angle between the polarization and the magnetization. This observation can be accounted for by the existence of spin-dependent gaps in the electronic band structure of the ferromagnets.
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Huge excitonic effects in layered hexagonal boron nitride. PHYSICAL REVIEW LETTERS 2006; 96:026402. [PMID: 16486604 DOI: 10.1103/physrevlett.96.026402] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Indexed: 05/06/2023]
Abstract
The all-electron GW approximation energy band gap of bulk hexagonal boron nitride is shown to be of indirect type. The resulting computed in-plane polarized optical spectrum, obtained by solving the Bethe-Salpeter equation for the electron-hole two-particle Green function, is in excellent agreement with experiment and has a strong anisotropy compared to out-of-plane polarized spectrum. A detailed analysis of the excitonic structures within the band gap shows that the low-lying excitons belong to the Frenkel class and are tightly confined within the layers. The calculated exciton binding energy is much larger than that obtained by Watanabe et al. [Nat. Mater. 3, 404 (2004).] based on a Wannier model assuming h-BN to be a direct-band-gap semiconductor.
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Multiple-scattering theory of x-ray magnetic circular dichroism: Implementation and results for the iron K edge. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:7334-7349. [PMID: 9984356 DOI: 10.1103/physrevb.54.7334] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Calculated optical properties of Si, Ge, and GaAs under hydrostatic pressure. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:2480-2490. [PMID: 9986095 DOI: 10.1103/physrevb.54.2480] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Optical and electronic-structure study of cubic and hexagonal GaN thin films. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:8082-8091. [PMID: 9979806 DOI: 10.1103/physrevb.52.8082] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Prediction of an undimerized, insulating, antiferromagnetic ground state in halogen-bridged linear-chain Ni compounds. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:R6975-R6978. [PMID: 9979728 DOI: 10.1103/physrevb.52.r6975] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Accuracy of alloy partial densities of states as determined by valence-band photoelectron diffraction. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:9497-9507. [PMID: 9977610 DOI: 10.1103/physrevb.51.9497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Alouani et al. Reply. PHYSICAL REVIEW LETTERS 1994; 73:3599. [PMID: 10057426 DOI: 10.1103/physrevlett.73.3599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Calculated and measured uv reflectivity of SiC polytypes. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:10722-10726. [PMID: 9975172 DOI: 10.1103/physrevb.50.10722] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Final-state rule and the absorption spectra of 3d ferromagnets. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:16038-16041. [PMID: 10010743 DOI: 10.1103/physrevb.49.16038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Tuning of the charge-density wave in the halogen-bridged transition-metal linear-chain compounds. PHYSICAL REVIEW LETTERS 1993; 71:1415-1418. [PMID: 10055534 DOI: 10.1103/physrevlett.71.1415] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Ab initio calculation of the dimerization in the halogen-bridged transition-metal linear-chain compound Pt2Br6(NH3)4. PHYSICAL REVIEW LETTERS 1992; 69:3104-3107. [PMID: 10046726 DOI: 10.1103/physrevlett.69.3104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Anisotropy and oxygen-stoichiometry dependence of the dielectric tensor of YBa2Cu3O7- delta (0 <= delta <= 1). PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:217-224. [PMID: 9998237 DOI: 10.1103/physrevb.44.217] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Electronic and optical properties of strained Ge/Si superlattices. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:14597-14614. [PMID: 9997352 DOI: 10.1103/physrevb.43.14597] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Calculated elastic constants and structural properties of Mo and MoSi2. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:6500-6509. [PMID: 9998090 DOI: 10.1103/physrevb.43.6500] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Interband transitions in strain-symmetrized Ge4Si6 superlattices. PHYSICAL REVIEW LETTERS 1990; 65:1933-1936. [PMID: 10042401 DOI: 10.1103/physrevlett.65.1933] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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E2 interband transitions in AlxGa1-xAs alloys. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 41:2959-2965. [PMID: 9994065 DOI: 10.1103/physrevb.41.2959] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Anisotropy of the dielectric function in YBa2Cu3O6. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:7368-7371. [PMID: 9991147 DOI: 10.1103/physrevb.40.7368] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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X-ray absorption of YBa2Cu3O7: A band picture. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:837-840. [PMID: 9990999 DOI: 10.1103/physrevb.40.837] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Calculated ground-state and optical properties of potassium under pressure. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:8096-8106. [PMID: 9947514 DOI: 10.1103/physrevb.39.8096] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Calculated optical and structural properties of InP under pressure. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:7705-7712. [PMID: 9947451 DOI: 10.1103/physrevb.39.7705] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Optical properties of metallic silicon. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:12864-12867. [PMID: 9946255 DOI: 10.1103/physrevb.38.12864] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Interband transitions in ultrathin GaAs-AlAs superlattices. PHYSICAL REVIEW LETTERS 1988; 61:1643-1646. [PMID: 10038858 DOI: 10.1103/physrevlett.61.1643] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Calculated electronic properties of tetragonal crystalline Si-Ge alloys: Comparison to amorphous phases. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:1378-1383. [PMID: 9946400 DOI: 10.1103/physrevb.38.1378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Calculated optical properties of semiconductors. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 37:1167-1179. [PMID: 9944623 DOI: 10.1103/physrevb.37.1167] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Self-energy corrections to the ab initio band structure: Chromium. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:929-938. [PMID: 9942897 DOI: 10.1103/physrevb.36.929] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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