Article
Physics, Applied
Weipeng Wu, Charles Yaw Ameyaw, Matthew F. Doty, M. Benjamin Jungfleisch
Summary: This tutorial article discusses the progress made in understanding and utilizing interactions between electrons, spins, and phonons in solid state materials for terahertz spintronics applications. The focus is on the physical effects underlying the operation of spintronic THz emitters, with a review of historical background, current theoretical understanding, experimental techniques, synthesis methods, and recent developments in the field, including novel material platforms.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Multidisciplinary Sciences
Piyush Agarwal, Lisen Huang, Sze Ter Lim, Ranjan Singh
Summary: Energy-efficient spintronic technology holds tremendous potential for next-generation processors operating at terahertz frequencies. In this study, a nonlinear electric-field control of terahertz spin current-based emitters was demonstrated using a piezoelectric material. This breakthrough offers opportunities for the realization of tunable energy-efficient spintronic-photonic integrated platforms.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Sandeep Kumar, Anand Nivedan, Arvind Singh, Yogesh Kumar, Purnima Malhotra, Marc Tondusson, Eric Freysz, Sunil Kumar
Summary: THz pulses are generated from femtosecond pulse-excited ferromagnetic/nonmagnetic spintronic heterostructures via inverse spin Hall effect. The highest possible THz signal strength from spintronic THz emitters is limited by the optical damage threshold of the corresponding heterostructures at the excitation wavelength. For the thickness-optimized spintronic heterostructure, the THz generation efficiency does not saturate with the excitation fluence even up till the damage threshold.
Article
Multidisciplinary Sciences
Cormac McDonnell, Junhong Deng, Symeon Sideris, Tal Ellenbogen, Guixin Li
Summary: The use of broadband THz emitters based on Pancharatnam-Berry phase nonlinear metasurfaces allows for precise control and tuning of THz waves.
NATURE COMMUNICATIONS
(2021)
Review
Nanoscience & Nanotechnology
Evangelos Th Papaioannou, Rene Beigang
Summary: THz spintronics is a research direction that combines magnetism, optical physics, and ultrafast photonics. The experimental scheme involves using femtosecond laser pulses to trigger spin and charge dynamics in thin films. Key challenges include increasing intensity, shaping frequency bandwidth, and controlling the transport of ultrafast spin current for radiation source control.
Article
Materials Science, Multidisciplinary
Piyush Agarwal, Yingshu Yang, Rohit Medwal, Hironori Asada, Yasuhiro Fukuma, Marco Battiato, Ranjan Singh
Summary: Femtosecond laser-induced photoexcitation of ferromagnet/heavy metal heterostructures can emit broadband terahertz frequencies. The phenomenon is mainly attributed to the direct photoexcitation of the ferromagnet layer, but it is also influenced by a secondary excitation caused by hot electrons from the heavy metal layer.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Physics, Applied
Finn-Frederik Stiewe, Tristan Winkel, Yuta Sasaki, Tobias Tubandt, Tobias Kleinke, Christian Denker, Ulrike Martens, Nina Meyer, Tahereh Sadat Parvini, Shigemi Mizukami, Jakob Walowski, Markus Muenzenberg
Summary: We investigate the generation of local THz fields using spintronic THz emitters to improve the resolution for micrometer-sized imaging. By employing optical laser pulses as a pump, the THz field generation can be localized to the area of laser beam focusing. Through the use of scanning techniques and gold test patterns, we achieve sub-micrometer spatial resolution at the dimensions of the laser spot size.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Elias Kueny, Anne-Laure Calendron, Sven Velten, Lars Bocklage, Franz X. Kaertner, Ralf Roehlsberger
Summary: State-of-the-art THz spintronic emitters require a continuous magnetic field for saturation. This study demonstrates that depositing ferromagnetic layers at an oblique angle can confine magnetization to a chosen in-plane axis and maintain saturation without an external magnetic field. By employing this method, THz emitters structured as spin valves can be built, allowing control over the emission and polarization of THz radiation through an external magnetic field.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Symeon Sideris, Hu Zixian, Cormac McDonnell, Guixin Li, Tal Ellenbogen
Summary: The development of efficient sources for generating and shaping terahertz (THz) emission is crucial for the advancement of THz technology. This study demonstrates the use of near-field interactions in nonlinear Pancharatnam-Berry phase plasmonic metasurfaces to achieve precise and continuous control over the local amplitude of the emitted field, allowing for the generation of precisely shaped THz beams. The ability to generate structured beams holds immense potential for enhancing imaging resolution and contrast in THz technology applications.
Article
Multidisciplinary Sciences
Laura Scheuer, Moritz Ruhwedel, Dimitrios Karfaridis, Isaak G. Vasileiadis, Dominik Sokoluk, Garik Torosyan, George Vourlias, George P. Dimitrakopoulos, Marco Rahm, Burkard Hillebrands, Thomas Kehagias, Rene Beigang, Evangelos Th. Papaioannou
Summary: Recent developments in nanomagnetism and spintronics have enabled the use of ultrafast spin physics for terahertz emission. This paper focuses on the impact of the interface between ferromagnetic (FM) and non-magnetic (NM) thin film heterostructures on terahertz emission, specifically by investigating the modification of the Fe/Pt interface using an ordered L1(0)-FePt alloy interlayer. It is found that a Fe/L1(0)-FePt (2 nm)/ Pt configuration shows significantly higher terahertz emission amplitude compared to a Fe/Pt bilayer structure, depending on the extent of alloying on either side of the interface. This trilayer structure opens up new possibilities for material choices in the next generation of spintronic terahertz emitters.
Article
Optics
Tim Vogel, Alan Omar, Samira Mansourzadeh, Frank Wulf, Natalia Martin Sabanes, Melanie Muller, Tom S. Seifert, Alexander Weigel, Gerhard Jakob, Mathias Klaui, Ioachim Pupeza, Tobias Kampfrath, Clara J. Saraceno
Summary: This article explores the power scaling behavior of tri-layer spintronic emitters and finds that a reflection geometry with back-side cooling is ideally suited for high-average-power excitation. By analyzing the effects of repetition rate on THz power generation, it is revealed that conversion efficiency is predominantly determined by incident fluence. These findings provide guidelines for scaling the power of THz radiation emitted by spintronic emitters using state-of-the-art femtosecond sources.
Article
Physics, Applied
Nishtha Chopra, Justas Deveikis, James Lloyd-Hughes
Summary: The spatial profile of pulsed THz radiation can be controlled electrically using a multi-pixel photoconductive emitter made of interdigitated electrodes on GaAs. By activating individual pixels, the transverse position of the THz beam's focus can be changed off-axis and non-Gaussian beam shapes can be created. The diffraction-limited performance is determined, and a condition for effective beam steering is derived based on the Abbe and Sparrow criteria.
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Dominik Schulz, Benjamin Schwager, Jamal Berakdar
Summary: This study demonstrates novel metastructures of spintronic THz emitters (STEs) for shaping the vectorial focal distribution of emitted THz radiations. Through simulations, the researchers show that the metastructures are able to generate broadband THz fields with designed features and discuss the potential of these fields in studying magnetic, multiferroic, and chiral structures. Additionally, the study finds that subwavelength features of the near fields can be tuned by controlling the magnetization of the metastructures.
Article
Physics, Applied
J. Hawecker, E. Rongione, A. Markou, S. Krishnia, F. Godel, S. Collin, R. Lebrun, J. Tignon, J. Mangeney, T. Boulier, J-M George, C. Felser, H. Jaffres, S. Dhillon
Summary: In this work, the optimization of spintronic terahertz emitters through various approaches is presented. These approaches include the application of multi-stacks, spin-sinks, and semi-metals, which result in significant enhancements of the emitted terahertz field. The study also explores the relation between spin diffusion length and spin-sink using THz spectroscopy.
APPLIED PHYSICS LETTERS
(2022)
Article
Multidisciplinary Sciences
Bjoern Niedzielski, Dominik Schulz, Jamal Berakdar
Summary: This study demonstrates the potential of spintronic THz emitters based on metastructures to drive and modulate the superconducting order parameter, leading to the topological texture of THz fields. Numerical simulations illustrate the formation of Abrikosov vortices and the local modification of superconducting properties in nanoscale samples.
SCIENTIFIC REPORTS
(2022)
Article
Astronomy & Astrophysics
M. Antonello, E. Barberio, T. Baroncelli, J. Benziger, L. J. Bignell, I. Bolognino, F. Calaprice, S. Copello, D. D'Angelo, G. D'Imperio, I. Dafinei, G. Di Carlo, M. Diemoz, A. Di Ludovico, A. R. Duffy, F. Froborg, G. K. Giovanetti, E. Hoppe, A. Ianni, L. Ioannucci, S. Krishnan, G. J. Lane, I. Mahmood, A. Mariani, P. McGee, P. Montini, J. Mould, F. Nuti, D. Orlandi, M. Paris, V. Pettinacci, L. Pietrofaccia, D. Prokopovich, S. Rahatlou, N. Rossi, A. Sarbutt, E. Shields, M. J. Souza, A. E. Stuchbery, B. Suerfu, C. Tomei, P. Urquijo, C. Vignoli, M. Wada, A. Wallner, A. G. Williams, J. Xu, M. Zurowski
ASTROPARTICLE PHYSICS
(2019)
Article
Physics, Particles & Fields
M. Antonello, E. Barberio, T. Baroncelli, J. Benziger, L. J. Bignell, I. Bolognino, F. Calaprice, S. Copello, D. D'Angelo, G. D'Imperio, I. Dafinei, G. Di Carlo, M. Diemoz, A. Di Ludovico, W. Dix, A. R. Duffy, F. Froborg, G. K. Giovanetti, E. Hoppe, A. Ianni, L. Ioannucci, S. Krishnan, G. J. Lane, I. Mahmood, A. Mariani, M. Mastrodicasa, P. Montini, J. Mould, F. Nuti, D. Orlandi, M. Paris, V. Pettinacci, L. Pietrofaccia, D. Prokopovic, S. Rahatlou, N. Rossi, A. Sarbutt, E. Shields, M. J. Souza, A. E. Stuchbery, B. Suerfu, C. Tomei, V. Toso, P. Urquijo, C. Vignoli, M. Wada, A. Wallner, A. G. Williams, J. Xu
EUROPEAN PHYSICAL JOURNAL C
(2019)
Article
Instruments & Instrumentation
J. Ashenfelter, A. B. Balantekin, C. Baldenegro, H. R. Band, C. D. Bass, D. E. Bergeron, D. Berish, L. J. Bignell, N. S. Bowden, J. Boyle, J. Bricco, J. P. Brodsky, C. D. Bryan, A. Bykadorova Telles, J. J. Cherwinka, T. Classen, K. Commeford, A. Conant, A. A. Cox, D. Davee, D. Dean, G. Deichert, M. Diwan, M. J. Dolinski, A. Erickson, M. Febbraro, B. T. Foust, J. K. Gaison, A. Galindo-Uribarri, C. Gilbert, K. Gilje, A. Glenn, B. W. Goddard, B. Hackett, K. Han, S. Hans, A. B. Hansell, K. M. Heeger, B. Heffron, J. Insler, D. E. Jaffe, X. Ji, D. C. Jones, K. Koehler, O. Kyzylova, C. E. Lane, T. J. Langford, J. LaRosa, B. R. Littlejohn, F. Lopez, X. Lu, D. A. Martinez Caicedo, J. T. Matta, R. D. McKeown, M. P. Mendenhall, H. J. Miller, J. Minock, P. E. Mueller, H. P. Mumm, J. Napolitano, R. Neilson, J. A. Nikkel, D. Norcini, S. Nour, D. A. Pushin, X. Qian, E. Romero-Romero, R. Rosero, D. Sarenac, B. Seilhan, R. Sharma, P. T. Surukuchi, C. Trinh, M. A. Tyra, R. L. Varner, B. Viren, J. M. Wagner, W. Wang, B. White, C. White, J. Wilhelmi, T. Wise, H. Yao, M. Yeh, Y-R Yen, A. Zhang, C. Zhang, X. Zhang, M. Zhao
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
(2019)
Article
Physics, Applied
Hao Zhang, Joseph Horvat, R. A. Lewis, Rainer Adelung, Bodo Fiedler, Yogendra K. Mishra
JOURNAL OF APPLIED PHYSICS
(2020)
Editorial Material
Medicine, General & Internal
R. A. Lewis
BMJ-BRITISH MEDICAL JOURNAL
(2020)
Article
Physics, Particles & Fields
M. Antonello, I. J. Arnquist, E. Barberio, T. Baroncelli, J. Benziger, L. J. Bignell, I Bolognino, F. Calaprice, S. Copello, I Dafinei, D. D'Angelo, G. D'Imperio, M. D'Incecco, G. Di Carlo, M. Diemoz, A. Di Giacinto, A. Di Ludovico, W. Dix, A. R. Duffy, E. Hoppe, A. Ianni, M. Iannone, L. Ioannucci, S. Krishnan, G. J. Lane, I Mahmood, A. Mariani, S. Milana, J. Mould, F. Nuti, D. Orlandi, V Pettinacci, L. Pietrofaccia, S. Rahatlou, F. Scutti, M. Souza, A. E. Stuchbery, B. Suerfu, C. Tomei, P. Urquijo, C. Vignoli, A. Wallner, M. Wada, A. G. Williams, A. Zani, M. Zurowski
Summary: This study reports the first characterization of the NaI-33 crystal, showing its extremely low contamination levels and acceptable energy performance. The research also demonstrates analysis techniques developed for noise rejection and detection of intrinsic radioactivity.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Chemistry, Physical
T. J. Sanders, J. L. Allen, J. Horvat, R. A. Lewis
Summary: The terahertz transmittance spectra of l-alanine were measured using a single crystal for the first time, revealing 18 absorptions between 20 and 250 cm(-1). As temperature increased, all modes exhibited spectral redshift except for the 91 and 128 cm(-1) modes, which showed anomalous blueshifting behavior. Density-functional theory modeling helped assign all observed modes, confirming the phonon origin of the absorptions.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Instruments & Instrumentation
Lucia M. Lepodise, Roger A. Lewis, Evan Constable, Elise Pogson, Stephen D. Joseph, Josip Horvat
Summary: Terra preta, a fertile anthropogenic soil found in the Amazon basin, is rich in aromatic carbons, which differentiates it from surrounding soils. The study conducted Fourier transform infrared spectroscopy and found that the spectra of terra preta and organic fertilizers were similar in the 150-500 cm(-1) range, but different from natural soils. This suggests that the content of aromatic carbons in terra preta and organic fertilizers is distinct from soils containing bushfire chars and those produced solely by bacterial and fungal activities, highlighting the importance of biochar preparation conditions.
APPLIED SPECTROSCOPY
(2022)
Review
Physics, Multidisciplinary
R. A. Lewis
Summary: A wide range of physical phenomena with frequencies ranging from 0.1-10 THz exist, including phononic, electronic, and mixed modes of oscillations. These fundamental phenomena are then utilized in specific devices to generate, manipulate, and detect terahertz radiation.
ANNALEN DER PHYSIK
(2023)
Article
Physics, Multidisciplinary
J. L. Allen, T. J. Sanders, J. Horvat, R. A. Lewis, K. C. Rule
Summary: Density-functional theory is used to predict the frequency and dipole moment of molecular crystals' fundamental oscillations. However, previous studies have had shortcomings, such as the use of impure and diluted materials and the inability to distinguish different vibrational modes. This study overcomes these obstacles by analyzing the low-temperature polarized THz spectra of single-crystal L-alanine and comparing them with density-functional theory calculations, resulting in corrected mode assignments and the discovery of unreported modes.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Physical
T. J. Sanders, J. L. Allen, J. Horvat, R. A. Lewis
Summary: In this study, the theoretical terahertz spectrum of the amino acid L-tyrosine has been calculated using density functional theory (DFT). A low-frequency mode that has not been previously reported was predicted. By introducing dispersion corrections, the PBE-d3 functional successfully observed a new resonance at 1.79 THz, which matched well with experimental data.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
T. J. Sanders, J. L. Allen, J. Horvat, R. A. Lewis
Summary: The terahertz (THz) spectrum of DL-alanine has been measured for the first time at cryogenic temperatures and with a pure sample. Temperature dependent spectra revealed redshifting, with increasing temperature, for the modes. The study suggests that molecular vibrations of DL-alanine are influenced by temperature and exhibit frequency shifts.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Hao Zhang, Qiao Yan, Joseph Horvat, Roger A. Lewis
Summary: The study focused on developing a functional hydrogel with enhanced piezoresistive ability by combining SWCNT hydrogels and L-DOPA. The hybrid network showed potential for pressure-sensing applications and maintained enough free catechol groups to endow the desired properties. Various characterization techniques were utilized to study the L-DOPA-PAM-SWCNT hydrogel hybrid network.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Chemistry, Physical
A. D. Squires, Adam J. Zaczek, R. A. Lewis, Timothy M. Korter
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2020)
Article
Materials Science, Multidisciplinary
E. Constable, A. D. Squires, J. Horvat, R. A. Lewis, D. Appadoo, R. Plathe, P. Roy, J-B Brubach, S. deBrion, A. Pimenov, G. Deng