Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films   Excited   by Femtosecond Optical Pulse

Tonouchi, Masayoshi; Tani, Masahiko; Wang, Zhen; Sakai, Kiyomi; Tomozawa, S.; Hangyo, Masanori; Murakami, Yohei; Nakashima, S.

doi:10.1143/jjap.35.2624

Cited by 109 publications

(47 citation statements)

References 19 publications

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“…This suggests that the observed crystallographic anisotropy of THz emission observed in Figure 1d does not arise from the time-varying current density. The THz emission field (E J ) in free space is determined by the photogenerated current density J(t) using the following relationship: [12][13][14] E J ðtÞ / @JðtÞ @t (…”

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confidence: 99%

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO₃

Rana¹,

Kawayama²,

Mavani³

et al. 2009

Advanced Materials

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The vast majority of data-storage devices are based on ferroelectric or magnetic materials. [1,2] The magnetic-memory effect is derived from the spin order, while the ferroelectric memories are based on the spontaneous polarization of electric dipoles. In the quest for superior efficiencies, the operating speed of the devices based on these memories has become a major focus of research. The time needed for the memory parameter to respond to ultrafast electric, magnetic, or optical stimuli is vital to determine its operating speed. [3][4][5] The ultrafast dynamics of spin (magnetic) memory over a picosecond time scale upon femtosecond excitation is well established. [3][4][5][6][7][8][9][10][11] Upon femtosecond excitation, the spin reorientation or the ultrafast demagnetization in ferromagnetic and antiferromagnetic materials occurs in the time scale of 1-2 ps, which suggests that when subjected to ultrafast stimuli, the magnetic memory can be manipulated at an exceptionally high speeds. However, the analogous situation of the ultrafast functionality of spontaneous polarization in ferroelectric/multiferroic materials remains unknown.The use of terahertz (THz) radiation-based spectroscopic techniques [12][13][14][15][16][17][18] has uncovered phenomena in a wide range of materials, such as semiconductors, [15,16] strongly correlated electron systems, [11][12][13][14][15] magnetic films, [9][10][11] and biological molecules.[19] The emission of THz radiation provides a direct measure of transient change in electric/magnetic fields over a picosecond time scale. [9][10][11][12][13][14][15][16][17] In any medium, THz emission according to the Maxwell wave equation is governed bywhere E, eô, m, and t are the electric field, electric susceptibility of free space, magnetic permeability, and time, respectively. In this relationship, THz emission can occur through a time-varying current density (J) and/or polarization (P). The polarization can be decomposed into P ¼ P S þ P NL , which indicates that THz emission can be due to time-varying spontaneous polarization P S (such as partial/complete depolarization) and/or optical rectification in non-linear medium (P NL ). [12,13,16,17] While the latter is a well-established source of THz emission, [13,16] the effect of P S is not known. Terahertz emission due to P S is of great importance, as it is a direct means of probing the ultrafast polarization dynamics of ferroelectric memories. [20] It should also provide a better understanding of the time scale at which the electric dipoles in the spontaneous polarized state are accessible for read or write operations. This time scale is crucial in determining the operating speed of ferroelectric memory devices, thus paving the way to improve their efficiency and ultimately resulting in their widespread adoption in various technological applications. To realize this, it is essential to utilize a ferroelectric system with a large P S . A choice popular with many researchers is the room-temperature ferroelectric antiferromagnet, BiFeO 3 ....

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confidence: 99%

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO₃

Rana¹,

Kawayama²,

Mavani³

et al. 2009

Advanced Materials

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158

105

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“…emitters which rely on a superconducting-normal transition to achieve fast switching times. 17 However, since VO 2 devices can be operated at room temperature, this constitutes a substantial advantage over superconducting devices. Additionally, VO 2 devices are similar to terahertz emitters based on the rapid heating and subsequent demagnetization of ferromagnetic films.…”

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confidence: 99%

Broadband terahertz generation using the semiconductor-metal transition in VO2

et al. 2016

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We report the design, fabrication, and characterization of broadband terahertz emitters based on the semiconductor-metal transition in thin film VO2 (vanadium dioxide). With the appropriate geometry, picosecond electrical pulses are generated by illuminating 120 nm thick VO2 with 280 fs pulses from a femtosecond laser. These ultrafast electrical pulses are used to drive a simple dipole antenna, generating broadband terahertz radiation.

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“…A variety of electronic materials can emit THz radiation upon being illuminated with femtosecond laser [2][3][4][5]. The emission properties such as amplitude and waveforms reflect the nature of materials.…”

Section: Introductionmentioning

confidence: 99%

Laser terahertz emission microscopy

Murakami

Tonouchi

2008

Comptes Rendus. Physique

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Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse

Cited by 109 publications

References 19 publications

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO₃

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO₃

Broadband terahertz generation using the semiconductor-metal transition in VO2

Laser terahertz emission microscopy

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Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse

Cited by 109 publications

References 19 publications

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO3

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO3

Broadband terahertz generation using the semiconductor-metal transition in VO2

Laser terahertz emission microscopy

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Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO₃

Understanding the Nature of Ultrafast Polarization Dynamics of Ferroelectric Memory in the Multiferroic BiFeO₃