Intrinsic charge transfer in mixed halide compounds PtX_(x)X'_(1-x ) was studied in the framework of the two-band extended Pielerls-Hubbard model.It was found that the number of transferred charges can be a fracti...Intrinsic charge transfer in mixed halide compounds PtX_(x)X'_(1-x ) was studied in the framework of the two-band extended Pielerls-Hubbard model.It was found that the number of transferred charges can be a fraction times of the electronic charge.The maximum amount of the transferred charges will occur at a certain proportion x for a given mixed compound.展开更多
Considering the special carriers in organic semiconductors, the spin polarized current under electric field in a ferromagnetic/organic semiconductor system is theoretically studied. Based on the spin-diffusion theory,...Considering the special carriers in organic semiconductors, the spin polarized current under electric field in a ferromagnetic/organic semiconductor system is theoretically studied. Based on the spin-diffusion theory, the current spin polarization under the electric field is obtained. It is found that electric field can enhance the current spin polarization.展开更多
A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K.The sample performance was demonstrated to be analogous to that of a bipolar transistor.The ...A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K.The sample performance was demonstrated to be analogous to that of a bipolar transistor.The maximal value of the output pulse voltage between Cu and Fe layers could reach the order of severalμV when the bias current between Co and Cu layers was 10μA.The interface roughness,photograph of material,magnetic loop and injection characteristic curves have been measured.Some important points on this topic have been discussed.展开更多
Based on nonequilibrium Green＇s function and first-principles calculations, we investigate the change in molecular conductance caused by different adsorption sites with the presence of additional Au atom around the m...Based on nonequilibrium Green＇s function and first-principles calculations, we investigate the change in molecular conductance caused by different adsorption sites with the presence of additional Au atom around the metal- molecule contact in the system that benzene sandwiched between two Au（111） leads. The motivation is the variable situations that may arise in break junction experiments. Numerical results show that the enhancement of conductance induced by the presence of additional Au is dependent on the adsorption sites of anchoring atom. When molecule is located on top site with the presence of additional Au atoms, it can increase molecular conductance remarkably and present negative differential resistance under applied bias which cannot be found in bridge and hollow sites. Furthermore, the effects of different distance between additional Au and sulfur atoms in these three adsorption sites are also discussed.展开更多
La0.67Ca0.33MnO3/Alq3/Co sandwiched-structure organic spin valves are fabricated by vacuum thermal evaporation method. A giant magnetoresistance （GMR） of 14% is observed at low temperature lOOK. At 3OK, the magnetor...La0.67Ca0.33MnO3/Alq3/Co sandwiched-structure organic spin valves are fabricated by vacuum thermal evaporation method. A giant magnetoresistance （GMR） of 14% is observed at low temperature lOOK. At 3OK, the magnetoresistance can increase to 50%. The large GMR of the device is attributed to the high spin polarization and low conductivity of the La0.67Ca0.33MnO3 contact. The magnetoresistance AR/R and the coercive field of the Co electrode depend strongly on temperature. The large high-field magnetoresistance reported on La0.67Sr0.33MnO3/Alq3/Co organic spin valves [Nature 427 （2004） 821] is not observed in our La0.67Ca0.33MnO3/Alq3/Co organic spin valves.展开更多
We investigate the re-exciting process of a soliton, a polaron and a bipolaron in conjugated polymers. For a soliton case, the processes S^0 ＋ hv→ S^± P↓± and S^± ＋ hv→S^0 ＋P± will take plac...We investigate the re-exciting process of a soliton, a polaron and a bipolaron in conjugated polymers. For a soliton case, the processes S^0 ＋ hv→ S^± P↓± and S^± ＋ hv→S^0 ＋P± will take place, where S^0 ,S^± and p^± express a neutral soliton, charged solitons and charged polarons, respectively. For a polaron case, the processes P^± ＋ hv→ p^↓± ＋ Bp^±2 will occur, where BP^±2 expresses a charged bipolaron with two electronic units. For a bipolaron case, the processes BP^±2 ＋ hv→ P^± ＋ P^± and BP^±2 ＋ hv→ BP^＋2 ＋ E0 are obtained.展开更多
Recent progress in organic spintronics is given an informative overview, covering spin injection, detection, and trans-port in organic spin valve devices, and the magnetic field effect in organic semiconductors （OSCs...Recent progress in organic spintronics is given an informative overview, covering spin injection, detection, and trans-port in organic spin valve devices, and the magnetic field effect in organic semiconductors （OSCs）. In particular, we focus on our own recent work in spin injection and the organic magnetic field effect （OMFE）.展开更多
For the organic magnetoresistance （OMAR） effect, we suggest a spin-related hopping of carriers （polarons） based on Marcus theory. The mobility of polarons is calculated with the master equation （ME） and then the...For the organic magnetoresistance （OMAR） effect, we suggest a spin-related hopping of carriers （polarons） based on Marcus theory. The mobility of polarons is calculated with the master equation （ME） and then the magnetoresistance （MR） is obtained. The theoretical results are consistent with the experimental observation. Especially, the sign inversion of the MR under different driving bias voltages found in the experiment is predicted. Besides, the effects of molecule disorder, hyperfine interaction （HFI）, polaron localization, and temperature on the MR are investigated.展开更多
We have studied the electric-field-driven motion of a polaron by solving the time-dependent SchrSdinger equation nonadiabatically and the lattice equation of motion simultaneously. It is found that the polaron may exp...We have studied the electric-field-driven motion of a polaron by solving the time-dependent SchrSdinger equation nonadiabatically and the lattice equation of motion simultaneously. It is found that the polaron may experience two sequent transitions under high fields; one is the transition from the subsonic to the supersonic state, and the other from the supersonic to dissociated state. The acoustic mode is decoupled from the charge when the polaron moves at a speed faster than the sound speed, and then the optical mode is decoupled at the second transition to make the polaron dissociate completely.展开更多
According to the one-dimensional antiresonance effect （Wang X R, Wang Y and Sun Z Z 2003 Phys. Rev. B 65 193402）, we propose a possible spin-polarized current generation device. Our proposed model consists of one ch...According to the one-dimensional antiresonance effect （Wang X R, Wang Y and Sun Z Z 2003 Phys. Rev. B 65 193402）, we propose a possible spin-polarized current generation device. Our proposed model consists of one chain and an impurity coupling to the chain. The energy level of the impurity can be occupied by an electron with a specific spin, and the electron with such a spin is blocked because of the antiresonance effect. Based on this phenomenon our model can generate the spin-polarized current flowing through the chain due to different polarization rates. On the other hand, the device can also be used to measure the generated spin accumulation. Our model is feasible with today＇s technology.展开更多
基金Supported by the Doctoral Foundation of the National Education Committee of China。
文摘Intrinsic charge transfer in mixed halide compounds PtX_(x)X'_(1-x ) was studied in the framework of the two-band extended Pielerls-Hubbard model.It was found that the number of transferred charges can be a fraction times of the electronic charge.The maximum amount of the transferred charges will occur at a certain proportion x for a given mixed compound.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10574082 and 10474056, and the Natural Science Foundation of Shandong Province under Grant No Z2005A01.
文摘Considering the special carriers in organic semiconductors, the spin polarized current under electric field in a ferromagnetic/organic semiconductor system is theoretically studied. Based on the spin-diffusion theory, the current spin polarization under the electric field is obtained. It is found that electric field can enhance the current spin polarization.
基金Supported by the National Natural Science Foundation of China under Grant No.59731010.
文摘A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K.The sample performance was demonstrated to be analogous to that of a bipolar transistor.The maximal value of the output pulse voltage between Cu and Fe layers could reach the order of severalμV when the bias current between Co and Cu layers was 10μA.The interface roughness,photograph of material,magnetic loop and injection characteristic curves have been measured.Some important points on this topic have been discussed.
基金Supported by the Natural Science Foundation of Shandong Province and the National Natural Science Foundations of China under Grant Nos.10574082 and Z2005A01.
文摘Based on nonequilibrium Green＇s function and first-principles calculations, we investigate the change in molecular conductance caused by different adsorption sites with the presence of additional Au atom around the metal- molecule contact in the system that benzene sandwiched between two Au（111） leads. The motivation is the variable situations that may arise in break junction experiments. Numerical results show that the enhancement of conductance induced by the presence of additional Au is dependent on the adsorption sites of anchoring atom. When molecule is located on top site with the presence of additional Au atoms, it can increase molecular conductance remarkably and present negative differential resistance under applied bias which cannot be found in bridge and hollow sites. Furthermore, the effects of different distance between additional Au and sulfur atoms in these three adsorption sites are also discussed.
基金Supported by the National Natural Science Foundation of China under Grant No 60576039, and the National Key Basic Research and Development Programme of China under Grant No 2001CB610504.
文摘La0.67Ca0.33MnO3/Alq3/Co sandwiched-structure organic spin valves are fabricated by vacuum thermal evaporation method. A giant magnetoresistance （GMR） of 14% is observed at low temperature lOOK. At 3OK, the magnetoresistance can increase to 50%. The large GMR of the device is attributed to the high spin polarization and low conductivity of the La0.67Ca0.33MnO3 contact. The magnetoresistance AR/R and the coercive field of the Co electrode depend strongly on temperature. The large high-field magnetoresistance reported on La0.67Sr0.33MnO3/Alq3/Co organic spin valves [Nature 427 （2004） 821] is not observed in our La0.67Ca0.33MnO3/Alq3/Co organic spin valves.
基金Supported by the National Natural Science Foundations of China under Grant Nos 90103034 and 50323006, and the Fund from Tianjin University.
文摘We investigate the re-exciting process of a soliton, a polaron and a bipolaron in conjugated polymers. For a soliton case, the processes S^0 ＋ hv→ S^± P↓± and S^± ＋ hv→S^0 ＋P± will take place, where S^0 ,S^± and p^± express a neutral soliton, charged solitons and charged polarons, respectively. For a polaron case, the processes P^± ＋ hv→ p^↓± ＋ Bp^±2 will occur, where BP^±2 expresses a charged bipolaron with two electronic units. For a bipolaron case, the processes BP^±2 ＋ hv→ P^± ＋ P^± and BP^±2 ＋ hv→ BP^＋2 ＋ E0 are obtained.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB923402)the National Natural Science Foundation of China(Grant Nos.11174181 and 21161160445)the 111 Project,China(Grant No.B13029)
文摘Recent progress in organic spintronics is given an informative overview, covering spin injection, detection, and trans-port in organic spin valve devices, and the magnetic field effect in organic semiconductors （OSCs）. In particular, we focus on our own recent work in spin injection and the organic magnetic field effect （OMFE）.
基金supported by the National Basic Research Program of China(Grant No.2010CB923402)the National Natural Science Foundation of China(Grant Nos.11174181 and 21161160445)the Program of Introducing Talents of Discipline to Universities,China(Grant No.B13029)
文摘For the organic magnetoresistance （OMAR） effect, we suggest a spin-related hopping of carriers （polarons） based on Marcus theory. The mobility of polarons is calculated with the master equation （ME） and then the magnetoresistance （MR） is obtained. The theoretical results are consistent with the experimental observation. Especially, the sign inversion of the MR under different driving bias voltages found in the experiment is predicted. Besides, the effects of molecule disorder, hyperfine interaction （HFI）, polaron localization, and temperature on the MR are investigated.
基金Project supported by the Major Program of the National Natural Science Foundation of China （Grant Nos 10474056, 90403110 and 10574082）.
文摘We have studied the electric-field-driven motion of a polaron by solving the time-dependent SchrSdinger equation nonadiabatically and the lattice equation of motion simultaneously. It is found that the polaron may experience two sequent transitions under high fields; one is the transition from the subsonic to the supersonic state, and the other from the supersonic to dissociated state. The acoustic mode is decoupled from the charge when the polaron moves at a speed faster than the sound speed, and then the optical mode is decoupled at the second transition to make the polaron dissociate completely.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10904082 and 10875072)
文摘According to the one-dimensional antiresonance effect （Wang X R, Wang Y and Sun Z Z 2003 Phys. Rev. B 65 193402）, we propose a possible spin-polarized current generation device. Our proposed model consists of one chain and an impurity coupling to the chain. The energy level of the impurity can be occupied by an electron with a specific spin, and the electron with such a spin is blocked because of the antiresonance effect. Based on this phenomenon our model can generate the spin-polarized current flowing through the chain due to different polarization rates. On the other hand, the device can also be used to measure the generated spin accumulation. Our model is feasible with today＇s technology.
