Photo-modulated dynamic competition between metallic and insulating phases in a layered manganite

2014 ◽  
Vol 1636 ◽  
Author(s):  
Yuelin Li ◽  
Donald Walko ◽  
Qing’an Li ◽  
Yaohua Liu ◽  
Stephan Rosenkranz ◽  
...  
Keyword(s):  
Optical Excitation ◽  
Superlattice Reflection ◽  
Metallic Phase ◽  
Local Competition ◽  
Ultrafast Optical ◽  
Laser Fluences ◽  
Show Evidence ◽  
Jahn Teller ◽  
Insulating Phase ◽  
Reflection Intensity

ABSTRACTWe show evidence that the competition between the antiferromagnetic metallic phase and the charge- and orbital-ordered insulating phase at the reentrant phase boundary of a layered manganite, LaSr2Mn2O7, can be manipulated using ultrafast optical excitation. The time-dependent evolution of the Jahn-Teller superlattice reflection, the indicator of the formation of charge and orbital order, was measured at different laser fluences. The laser-induced change in the Jahn-Teller reflection intensity shows a reversal of sign between earlier (∼10 ns) and later (∼150 ns) times during the relaxation of the sample. This is consistent with a physics picture whereby the laser excitation modulates the local competition between the metallic and the insulating phases.

Spin Fluctuation Effect on Electrical Resistivity of La0.8Ca0.2MnO3 Manganite Nanoparticles

2015 ◽  
Vol 14 (04) ◽  
pp. 1550010 ◽  
Author(s):  
K. K. Choudhary
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Regime ◽  
Spin Fluctuation ◽  
Metallic Phase ◽  
Spin Fluctuations ◽  
Electron Interaction ◽  
Manganite Nanoparticles ◽  
Wide Range ◽  
Insulating Phase

The electrical resistivity ρ(T) of La 0.8 C 0.2 MnO 3 manganite nanoparticles (particle size 18 nm and 70 nm) significantly depends on temperature and size of nanoparticles. ρ(T) of 70 nm La 0.8 C 0.2 MnO 3 manganite exhibits metallic phase in low temperature regime (T < 250 K ), develops a maxima near 250 K and decrease with T at high temperatures (250 K < T < 300 K ). However, the ρ(T) of 18 nm La 0.8 C 0.2 MnO 3 manganite shows insulating phase in overall temperature regime, where resistivity decrease with temperature. The resistivity in metallic phase is theoretically analyzed by considering the strong spin fluctuations effect which is modelled using Drude–Lorentz type function. In addition to the spin fluctuation-induced contribution the electron-phonon and electron-electron ρe-e(T) = BT2 contributions are also incorporated for complete understanding of experimental data. The contributions to the resistivity by inherent acoustic phonons (ρac) as well as high frequency optical phonons (ρop) were estimated using Bloch–Gruneisen [BG] model of resistivity. It is observed that the resistivity contribution due to electron-electron interaction shows typical quadratic temperature dependence. Resistivity in Semiconducting/insulating phase is discussed with small polaron conduction (SPC) model. Finally the theoretically calculated resistivity compared with experimental data which found consistent in wide range of temperature.

Control of coherent magnetization precession in GaMnAs by ultrafast optical excitation

2008 ◽  
Vol 5 (8) ◽  
pp. 2637-2640 ◽  
Author(s):  
J. Qi ◽  
Y. Xu ◽  
X. Liu ◽  
J. K. Furdyna ◽  
I. E. Perakis ◽  
...  
Keyword(s):  
Optical Excitation ◽  
Ultrafast Optical ◽  
Magnetization Precession

scholarly journals Ultrafast optical excitation of coherent magnons in antiferromagnetic NiO

2017 ◽  
Vol 95 (17) ◽  
Author(s):  
Christian Tzschaschel ◽  
Kensuke Otani ◽  
Ryugo Iida ◽  
Tsutomu Shimura ◽  
Hiroaki Ueda ◽  
...  
Keyword(s):  
Optical Excitation ◽  
Ultrafast Optical

scholarly journals Ultrafast Modulation of Magnetization Dynamics in Ferromagnetic (Ga, Mn)As Thin Films

2018 ◽  
Vol 8 (10) ◽  
pp. 1880 ◽  
Author(s):  
Hang Li ◽  
Xinhui Zhang ◽  
Xinyu Liu ◽  
Margaret Dobrowolska ◽  
Jacek Furdyna
Keyword(s):  
Magnetic Anisotropy ◽  
Spin Dynamics ◽  
Optical Excitation ◽  
Laser Pulses ◽  
Time Resolved ◽  
Ultrafast Optical ◽  
Optical Effects ◽  
Out Of Plane ◽  
Linearly Polarized ◽  
Magnetization Precession

Magnetization precession induced by linearly polarized optical excitation in ferromagnetic (Ga,Mn)As was studied by time-resolved magneto-optical Kerr effect measurements. The superposition of thermal and non-thermal effects arising from the laser pulses complicates the analysis of magnetization precession in terms of magnetic anisotropy fields. To obtain insight into these processes, we investigated compressively-strained thin (Ga,Mn)As films using ultrafast optical excitation above the band gap as a function of pulse intensity. Data analyses with the gyromagnetic calculation based on Landau-Lifshitz-Gilbert equation combined with two different magneto-optical effects shows the non-equivalent effects of in-plane and out-of-plane magnetic anisotropy fields on both the amplitude and the frequency of magnetization precession, thus providing a handle for separating the effects of non-thermal and thermal processes in this context. Our results show that the effect of photo-generated carriers on magnetic anisotropy constitutes a particularly effective mechanism for controlling both the frequency and amplitude of magnetization precession, thus suggesting the possibility of non-thermal manipulation of spin dynamics through pulsed laser excitations.

Time-resolved thermal expansion of an STM tip after ultrafast optical excitation

1998 ◽  
Author(s):  
R. Huber ◽  
M. Koch ◽  
M. Perner ◽  
W. Spirkl ◽  
J. Feldmann
Keyword(s):  
Thermal Expansion ◽  
Optical Excitation ◽  
Time Resolved ◽  
Ultrafast Optical

Breaking Metals with Ultrafast Optical Excitation

2000 ◽  
Vol 11 (12) ◽  
pp. 47 ◽  
Author(s):  
Chunlei Guo ◽  
George Rodriguez ◽  
Ahmed Lobad ◽  
Antoinette J. Taylor
Keyword(s):  
Optical Excitation ◽  
Ultrafast Optical

scholarly journals Evolution of a band insulating phase from a correlated metallic phase

2007 ◽  
Vol 76 (16) ◽  
Author(s):  
Kalobaran Maiti ◽  
Ravi Shankar Singh ◽  
V. R. R. Medicherla
Keyword(s):  
Metallic Phase ◽  
Insulating Phase
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