Spin Solar Cell Phenomenon on a Single-Molecule Magnet (SMM) Impacted CoFeB-Based Magnetic Tunnel Junctions

Journal Article · Wed May 31 00:00:00 EDT 2023 · ACS Applied Electronic Materials

DOI:https://doi.org/10.1021/acsaelm.3c00369· OSTI ID:2281181

Savadkoohi, Marzieh ^[1]; Gopman, Daniel ^[2]; Suh, Pius ^[3]; Rojas-Dotti, Carlos ^[4]; Martínez-Lillo, José ^[4]; Tyagi, Pawan ^[3]

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1. University of the District of Columbia, Washington, DC (United States); National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States); University of the District of Columbia
2. National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States)
3. University of the District of Columbia, Washington, DC (United States)
4. University of Valencia (Spain)

The single-molecule magnet (SMM) is demonstrated here to transform conventional magnetic tunnel junctions (MTJs), a memory device used in present-day computers, into solar cells. For the first time, we demonstrated an electronic spin-dependent solar cell effect on an SMM-transformed MTJ under illumination from unpolarized white light. We patterned cross-junction-shaped devices to form a CoFeB/MgO/CoFeB-based MTJ. The MgO barrier thickness at the intersection between the two exposed junction edges was less than the SMM extent, which enabled the SMM molecules to serve as channels to conduct spin-dependent transport. The SMM channels yielded a region of long-range magnetic ordering around these engineered molecular junctions. Our SMM possessed a hexanuclear [Mn₆(μ₃-O)₂(H₂N-sao)₆(6-atha)₂(EtOH)₆] [H₂N-saoH = salicylamidoxime, 6-atha = 6-acetylthiohexanoate] complex and thioesters end groups to form bonds with metal films. SMM-doped MTJs were shown to exhibit a solar cell effect and yielded ≈80 mV open-circuit voltage and ≈10 mA/cm² saturation current density under illumination from one sun equivalent radiation dose. A room-temperature Kelvin Probe AFM (KPAFM) study provided direct evidence that the SMM transformed the electronic properties of the MTJ’s electrodes over a lateral area in excess of several thousand times larger in extent than the area spanned by the molecular junctions themselves. As a result, the decisive factor in observing this spin-photovoltaic effect is the formation of SMM spin channels between the two different ferromagnetic electrodes, which in turn is able to catalyze the long-range transformation in each electrode around the junction area.

• Research Organization: University of the District of Columbia, Washington, DC (United States)
• Sponsoring Organization: Generalitat Valenciana; National Science Foundation-CREST; Spanish Ministry of Science and Innovation; USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0003945
• OSTI ID: 2281181
• Journal Information: ACS Applied Electronic Materials, Journal Name: ACS Applied Electronic Materials Journal Issue: 6 Vol. 5; ISSN 2637-6113
• Publisher: ACS Publications
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
MTJ
SMM
electrodes
light
magnetic properties
molecules
photovoltaic effect
solar cell
spin