Singamaneni Group
Laboratory for Quantum and Nanomagnetism
The University of Texas at El Paso
Department of Physics
Research Interests
Emerging multifunctional materials such as 2D materials, perovskite solar cells, multiferroic and ferroelectric materials and devices, thin film deposition, magnetism and magneto-transport studies, organic and inorganic spintronics, graphene based materials, electron spin/paramagnetic resonance spectroscopy, point and complex defects, semiconducting materials.
Experimental Tools
Our main goal is to employ various measurement techniques using cutting edge instrumentation and analysis techniques to pinpoint the atomic origins and underlying mechanisms of magnetic interactions in various bulk and two-dimensional van der Waals materials for use in next generation devices. In addition to our interest in next generation spintronic devices, we are also interested in next generation energy production. In situ electron spin resonance (ESR) spectroscopy is used to investigate paramagnetic defect sites in nanocrystalline catalysts. In this method, a three electrode electrochemical cell is assembled inside a 4mm ESR tube. The tube is placed inside the ESR spectrometer for live studies of the paramagnetic species while the reaction occurs.
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The primary tools and techniques employed are our Quantum Design physical property measurement system (PPMS), Quantum Design Versalab vibrating sample magnetometer (VSM) and on-sight electron spin resonance (ESR) spectrometer, which are used to analyze a material's magnetic behavior and catalytic properties. With the PPMS and VSM we are able to do a variety of experiments which includes AC susceptibility, electrical transport measurements, thermal conductivity, and more. The VSM (50-400 K, 3T) (evercool) magnetometer is extensively used to perform magnetic (both, in-plane and out of plane), transport, heat capacity, and in-situ light induced measurements. While ESR on the other hand, is a extremely sensitive technique used to detect atomic defects in a variety of materials.
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Magnetic Properties
1. MPMS3 SQUID Magnetometer - has evercool option, does not require external liquid helium
Accessories and options:
-MPMS3 UV Fiber Optic Sample Holder System M315
-Select Option M315A for visible to Ultra-Violet measurements range
-Select Option M315B for visible to Infra Red measurements range.
-MPMS3 AC Susceptibility Measurement M350
-MPMS3 Horizontal Rotator M301
-MPMS3 Resistivity Kit C150B
-MPMS3 ETO KIT M605
-MPMS3 Sample Oven & High Vacuum System M303
-MPMS HMD PRESSURE CELL (0-1.3 GPa)
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2. Quantum Design Versalab VSM (50-400 K, ±3T) Magnetometer - has evercool option, does not require external liquid helium
Accessories and options:
-VSM
-ACMS
-AC and DC transport (I-V, R vs T) measurements
-Heat capacity (PI’s lab)
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3. Quantum Design Physical Properties Measurement System (PPMS) (2-400 K, ±5 T) Magnetometer
Accessories and options:
-Both the DC magnetization and AC susceptibility up to 3 kHz can be measured (PI’s lab)
-AC and DC transport (I-V, R vs T) measurements
-This instrument runs with liquid helium and attached with V310-UV DynaCool VSM
-Fiber Optic Sample Holder Probe (UV to Visible to IR range) V312A/B Fiber Optic Sample Holder with 300W Xenon Light Source
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4. Bruker X-band electron paramagnetic resonance (EPR) – Spectrometer (UTEP Chemistry)
X-band (9.43 GHz) EPR spectrometer with ever cool (4-700 K, ±1.5T) option, located in the Chemistry Department of UTEP. I am the lead user of this equipment and have continuous access. A dedicated Ph.D. level technician operates this equipment. It requires helium and nitrogen gases to perform low temperature measurements. It does not require external liquid helium to cool down the sample temperature. This instrument is coupled with UV LED (375 nm, 2mW) and HgXe light sources, and optical excitation will be done through a fiber ranging from UV to visible to IR light source. Time resolved (nanoseconds) EPR detection is also coupled with this existing spectrometer.
Collaborators
We are working alongside many of our peers and colleagues not only on-site at The University of Texas at El Paso, but across the United States and around the world
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Facilities run by our collaborators:
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1. Variable frequency EPR (NHMFL, FL)
Heterodyne Quasi-Optical Spectrometer: This 120-336 GHz instrument is coupled to a 12.5 tesla superconducting magnet with a homogeneity of 10-5 over a 10 mm sphere; Frequency: 9-336 GHz, Field: -12.5 to 12.5 tesla, Temperature: 1.5 – 400 K; Transmission Spectrometer: 24 – 660 GHz, Field: 17 tesla, Temperature: 3 – 309 K; W-Band HiPER Spectrometer: Frequency: 94 GHz, Field: 9 tesla, Temperature: 4 to 300 K,; XW-Band Bruker Pulsed Spectrometer: Frequency: 9 and 94 GHz, Field: 6 T superconducting magnet, Temperature: 4 K to 300 K. These instruments are coupled with UV LED (375 nm, 2mW) and HgXe light sources, and optical excitation will be done through a fiber ranging from UV to visible to IR light source. Time resolved EPR measurements can also be accessed at NHMFL.
2. Facilities at Center for Integrated Nanotechnologies (CINT) at Las Alamos National Lab (LANL)
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Pump-probe time-resolved MOKE measurements with optical excitation from THz to optical frequencies under the application of magnetic fields up to 8 T and temperature down to 1.5 K. At CINT, LANL, the LUMOS facility is equipped with ultrafast laser systems covering a broad spectral range that spans the far-infrared to the ultraviolet (UV) region of the electromagnetic spectrum. These systems enable a multitude of ultrafast spectroscopic experiments, including optical-pump terahertz-probe spectroscopy and terahertz emission spectroscopy, terahertz pumping with probe frequencies ranging from the far-infrared to the ultraviolet, and optical pump-probe spectroscopies where both pump and probe frequencies can be tuned over a wide (far-IR to UV) range.
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3. Density Functional Theory calculations at UTEP
UTEP provides office and lab space for the Electronic Structure group led by Dr. Baruah in the Department of Physics. The other computational facilities that exist in the university and the lab are: a central high performance computing facility with 700 cores, desktops, a web server for the group, and storage devices. A video conferencing facility also exists within PI’s department. Apart from the local resources, Dr. Baruah has computing allocations of nearly 1.5M SUs on NERSC supercomputer and 0.5M on XSEDE resources.
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4. Professor Paramekanti's group at the University of Toronto has access to SciNet, which is a high performance supercomputing network supported by the Compute Canada consortium. They have recently received a Fast Track multi-year computing grant to focus on the study of emergent magnetism and magnetization dynamics. His group will perform calculations to support our experimental findings on ultrafast pump-probe measurements.
​Others:
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Prof. Frank Tsui, UNC, Chapel Hill, NC, USA, for MOKE measurements
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Prof. Christian Binek and Prof. Alexei Gruverman, University of Nebraska, for in-situ magneto-electric measurements
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Dr. Grutter Alexander J, NIST, Maryland, for E-field induced polarized neutron reflectivity measurements
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Dr. Valeria Lauter, Oak Ridge National Laboratory (ORNL), USA, polarized neutron reflectivity measurements
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Dr. John Buadai, on advanced X-ray diffraction measurements, Oak Ridge National Laboratory (ORNL), USA
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Prof. James Tour, on Graphene nanoribbons, Rice University, USA
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Dr. Hans van Tol, Prof. Stephen Hill for high frequency ESR, National High Magnetic Field Laboratory, Tallahassee Florida
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Prof. Michael K. Bowman, on the advanced ESR experiments such as ENDOR, The University of Alabama
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Prof. Alex I. Smirnov, on multi-frequency and HYSCORE ESR measurements, The North Carolina State University
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Prof. Moshcalkov, on Pulsed Magnetic Field Measurements (~50 T), VSM, PPMS and SQUID measurements, K U Leuven, Belgium
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IMEC, Belgium
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Dr. Ikenna Nlebedim and postdoc Dr. Kinjal Gandha at Ames Laboratory, Iowa, on low temperature magnetic measurements using Superconductiong Quantum Interface Device (SQUID)
Funding
Nuclear Regulatory Commision
United States Department of Education
American Chemical Society Petroleum Research Fund
National Science Foundation
United States Department of Energy
