This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerize...This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerized phase, which exists in a narrow parameter region of the so-called ~/1 - J2 model, vanishes if the interchain frustration is weak and anisotropic. Therefore, it concludes that the frustrating interaction indeed plays an important role in producing such a phase. As a complementary to our previous investigation, it reaches a more complete picture of the quantum phase transition in the frustrated spin ladder systems.展开更多
The spin ladder with Dzyaloshinsky-Moriya interaction is investigated by using the quantum renormalization-group method.The entanglement and fidelity are periodic functions of the time and oscillate between zero and o...The spin ladder with Dzyaloshinsky-Moriya interaction is investigated by using the quantum renormalization-group method.The entanglement and fidelity are periodic functions of the time and oscillate between zero and one.The oscillation period decreases with either the interaction in the spin ladder or the Dzyaloshinsky-Moriya interaction increasing.When the system relates to the environment,both entanglement and fidelity oscillate with a damping rate related to intrinsic decoherence rate,the interaction in the spin ladder,and the Dzyaloshinsky-Moriya interaction.展开更多
A new process to synthesize polycrystalline samples of Sr14Cu24O41 was presented. Firstly, dry gel powder of Sr14Cu24O41 was synthesized by the citrates sol-gel method, using Sr（NO3）2, Cu（NO3）2, ethylene glycol an...A new process to synthesize polycrystalline samples of Sr14Cu24O41 was presented. Firstly, dry gel powder of Sr14Cu24O41 was synthesized by the citrates sol-gel method, using Sr（NO3）2, Cu（NO3）2, ethylene glycol and citrate acid as raw materials. Then, polycrystalline samples of Sr14Cu24O41 were prepared by solid-state reaction. Thermal Gravimetric and Differential Thermal Analysis（TG-DTA） showed that the temperature for solid-state reaction is at 942 ℃. The samples are identified to be single phase by X-ray Diffraction（XRD） and Scanning Electron Microscopy（SEM）. The SEM pictures showed that the first-step particles were at even size of about 100 nm by this technique. The electronic transport measurements showed that the doping compound were semiconductor with a crossover temperature T in the Arrhenius plot of the resistivity versus temprature.展开更多
Dimerized spin-1/2 ladders exhibit a variety of phase structures,which depend on the intra-chain and inter-chain spin exchange energies as well as on the dimerization pattern of the ladder.Using the density matrix ren...Dimerized spin-1/2 ladders exhibit a variety of phase structures,which depend on the intra-chain and inter-chain spin exchange energies as well as on the dimerization pattern of the ladder.Using the density matrix renormalization group(DMRG)algorithm,we study critical properties of the bond-alternating two-leg Heisenberg spin ladder with diagonal interaction J_(×).Two types of spin systems,staggered dimerized antiferromagnetic ladder and columnar dimerized ferro-antiferromagnetic couplings ladder,are investigated.To clarify the phase transition behaviors,we simultaneously analyze the string order parameter(SOP),the twisted order parameter(TOP),as well as a measurement of the quantum information analysis.Based on measuring this different observables,we establish the phase diagram accurately and give the fitting functions of the phase boundaries.In addition,the phase transition of cross-coupled spin ladder(in the absence of intrinsic dimerization)is also discussed.展开更多
The Zn2＋, Ni2＋ and Co3＋ doped Sr14Cu24041 compounds were synthesized by standard solid state method. X-ray diffraction results show that the changes in lattice parameters are very small. Selected area electron diff...The Zn2＋, Ni2＋ and Co3＋ doped Sr14Cu24041 compounds were synthesized by standard solid state method. X-ray diffraction results show that the changes in lattice parameters are very small. Selected area electron diffraction patterns （EDPs） show that the diffraction spots corresponding to the CuO2 chain substructure are extended to streaks along a＊ and b＊ directions for all the samples, while the diffraction spots produced merely by the Cu203 ladder substructure are still very sharp. This means that the periodicities of chains in a＊ and b＊ directions are partially destroyed upon doping ofZn, Ni and Co due to that the initial phase of each chain becomes a random variable. The temperature dependence of magnetic properties was measured for every sample. And the number of dimers in CuO2 chain per formula unit （f.u.） and dimer coupling constant are obtained by fitting the temperature dependence of the magnetic susceptibility. It is found that the degree of initial phase disorder is related to the order degree of magnetic sequence in CuO2 chain. For the un-doped sample, the decoupling of dimers is weak, the magnetic sequence is slightly destroyed, and the streaks in EDP are also very weak, which implies the degree of initial phase disorder in CuO2 chain is very low. When Zn2~ and Ni2＋ ions are doped, the number of dimers per f.u. decreases, and the intensity of diffraction streaks increases in comparison with the corresponding spots. Furthermore, when the high spin magnetic ions Co3＋ are doped, the number of holes in Sr14Cu24041 decreases, the magnetic sequence is destroyed very seriously, and the spots in EDP are extended to streaks almost completely. The phenomenon that the diffraction spots ofCuO2 chain extend to streaks in EDP appears as evidence that the magnetic sequence in the CuO2 chain is destroyed by doping of Zn, Ni, Co.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10874003)Ministry of Science and Technology of China (Grant No. 2006CB921300)
文摘This paper studies a spin ladder model which possesses frustrating interactions. By using both the bosonization and the density matrix renormalization group techniques, it shows that the intermediate columnar dimerized phase, which exists in a narrow parameter region of the so-called ~/1 - J2 model, vanishes if the interchain frustration is weak and anisotropic. Therefore, it concludes that the frustrating interaction indeed plays an important role in producing such a phase. As a complementary to our previous investigation, it reaches a more complete picture of the quantum phase transition in the frustrated spin ladder systems.
基金Supported by the National Natural Science Foundation of China under Grant No.11074184the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The spin ladder with Dzyaloshinsky-Moriya interaction is investigated by using the quantum renormalization-group method.The entanglement and fidelity are periodic functions of the time and oscillate between zero and one.The oscillation period decreases with either the interaction in the spin ladder or the Dzyaloshinsky-Moriya interaction increasing.When the system relates to the environment,both entanglement and fidelity oscillate with a damping rate related to intrinsic decoherence rate,the interaction in the spin ladder,and the Dzyaloshinsky-Moriya interaction.
基金the National Natural Science Foundation of China(No.10474074)State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology)(No.WUT 2004 M03)
文摘A new process to synthesize polycrystalline samples of Sr14Cu24O41 was presented. Firstly, dry gel powder of Sr14Cu24O41 was synthesized by the citrates sol-gel method, using Sr（NO3）2, Cu（NO3）2, ethylene glycol and citrate acid as raw materials. Then, polycrystalline samples of Sr14Cu24O41 were prepared by solid-state reaction. Thermal Gravimetric and Differential Thermal Analysis（TG-DTA） showed that the temperature for solid-state reaction is at 942 ℃. The samples are identified to be single phase by X-ray Diffraction（XRD） and Scanning Electron Microscopy（SEM）. The SEM pictures showed that the first-step particles were at even size of about 100 nm by this technique. The electronic transport measurements showed that the doping compound were semiconductor with a crossover temperature T in the Arrhenius plot of the resistivity versus temprature.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474218 and 11575116).
文摘Dimerized spin-1/2 ladders exhibit a variety of phase structures,which depend on the intra-chain and inter-chain spin exchange energies as well as on the dimerization pattern of the ladder.Using the density matrix renormalization group(DMRG)algorithm,we study critical properties of the bond-alternating two-leg Heisenberg spin ladder with diagonal interaction J_(×).Two types of spin systems,staggered dimerized antiferromagnetic ladder and columnar dimerized ferro-antiferromagnetic couplings ladder,are investigated.To clarify the phase transition behaviors,we simultaneously analyze the string order parameter(SOP),the twisted order parameter(TOP),as well as a measurement of the quantum information analysis.Based on measuring this different observables,we establish the phase diagram accurately and give the fitting functions of the phase boundaries.In addition,the phase transition of cross-coupled spin ladder(in the absence of intrinsic dimerization)is also discussed.
基金Funded by the National Natural Science Foundation of China(Nos.10674105 and 50471028)
文摘The Zn2＋, Ni2＋ and Co3＋ doped Sr14Cu24041 compounds were synthesized by standard solid state method. X-ray diffraction results show that the changes in lattice parameters are very small. Selected area electron diffraction patterns （EDPs） show that the diffraction spots corresponding to the CuO2 chain substructure are extended to streaks along a＊ and b＊ directions for all the samples, while the diffraction spots produced merely by the Cu203 ladder substructure are still very sharp. This means that the periodicities of chains in a＊ and b＊ directions are partially destroyed upon doping ofZn, Ni and Co due to that the initial phase of each chain becomes a random variable. The temperature dependence of magnetic properties was measured for every sample. And the number of dimers in CuO2 chain per formula unit （f.u.） and dimer coupling constant are obtained by fitting the temperature dependence of the magnetic susceptibility. It is found that the degree of initial phase disorder is related to the order degree of magnetic sequence in CuO2 chain. For the un-doped sample, the decoupling of dimers is weak, the magnetic sequence is slightly destroyed, and the streaks in EDP are also very weak, which implies the degree of initial phase disorder in CuO2 chain is very low. When Zn2~ and Ni2＋ ions are doped, the number of dimers per f.u. decreases, and the intensity of diffraction streaks increases in comparison with the corresponding spots. Furthermore, when the high spin magnetic ions Co3＋ are doped, the number of holes in Sr14Cu24041 decreases, the magnetic sequence is destroyed very seriously, and the spots in EDP are extended to streaks almost completely. The phenomenon that the diffraction spots ofCuO2 chain extend to streaks in EDP appears as evidence that the magnetic sequence in the CuO2 chain is destroyed by doping of Zn, Ni, Co.
