The mixed spin-(1,1/2) Ising-Heisenberg double sawtooth ladder containing mixture of both spin-1 and spin-1/2 nodal atoms, and the spin-1/2 interstitial dimers is approximately solved by the transfer-matrix method. Here, we study in detail the ground-state phase diagrams, also influences of the bilinear exchange coupling on the rungs and cyclic four-spin exchange interaction in square plaquette of each block on the magnetization and magnetic susceptibility of the suggested ladder at low temperature. Such a double sawtooth ladder may be found in a Shastry-Sutherland Lattice-type. In spite of odd and even blocks spin ordering are different from each other, but due to the commutation relation between all different block Hamiltonians, phase diagrams, magnetization behavior and thermodynamic properties of the model are the same for odd and even blocks. We show that at low temperature, both exchange couplings can change the quality and quantity of the magnetization plateaus versus the magnetic field changes. Specially, we find a new magnetization plateau M/Ms = 5/6 for this model. Besides, we examine the magnetic susceptibility and specific heat of the model in detail. It is proven that behaviors of the magnetization and the magnetic susceptibility coincide at low temperature. The specific heat displays diverse temperature dependencies, which include a Schottky-type peak at a special temperature interval. We observe that with increase of the bilinear exchange coupling on the rungs, second peak temperature dependence grows.
Magnetization plateaus and enhanced magnetocaloric effect of a spin-1/2 Ising-Heisenberg and Heisenberg double sawtooth ladder with four-spin interaction
Fully frustrated Josephson junction ladders with Mobius boundary conditions as topologically protected qubits
我们展示了如何通过使用具有Mobius边界条件的完全阻挫的约瑟夫森结阶梯（JJL）来实现“受保护”的量子比特。这种系统最近已经在扭曲共形场论（CFT）方法（Mod. Phys. Lett. A 15（2000）1679; Nucl.Phys.B641（2002）547），并且显示出发展通量分级现象（Eur. J. B 49（2006）83）。在将系统的基态的拓扑性质与半通量量子的存在联系起来时，充分利用了“闭合”几何的相关性，并预测了拓扑秩序的出现（JSTAT（2005）P03006）。本文分析了基态在绝热磁通量变化下的稳定性和变换性质，并提出了实现防止退相干的固态量子比特的深刻后果。
N-leg integer-spin ladders and tubes in commensurate external fields -Nonlinear sigma model approach-
本文研究了具有反铁磁链内耦合的N臂整数自旋梯和管的低能性质。在奇腿管，自动对焦横档耦合造成挫折。为了系统地处理所有梯和管，我们应用基于非线性西格玛模型的Sénéchal方法[Phys. Rev. B 52，15319（1995）]。这种策略在弱链间（梯级）耦合机制中是有效的。我们发现所有的阻挫管都具有六重简并自旋1的磁振子带，作为最低激发态，而其他的阶梯和管具有标准的三重简并带。我们还考虑了四种塞曼项的影响：均匀的，交错只沿梯级，只沿链，或两个方向。上述无场情形的预测意味着，由于双简并最低磁振子在阻挫管中的凝聚，足够强的均匀场产生双组分Tomonaga-Luttinger液体（TLL）。相反，在所有其他系统中，场诱导标准的单分量TLL。这一点得到了基于金兹伯格-朗道理论的对称性和玻色子化论点的支持。玻色化还表明，当均匀场变大，次低磁振子带接触零能线时，双分量TLL消失，出现单分量TLL。在磁化过程中，这种转变可以被观察到为尖点奇异性。对具有交错Zeeman项的一维AF自旋系统的分析表明，双简并横磁振子和单纵磁振子的出现对于具有弱交错场的一维AF自旋系统是普遍的.
Phase transitions and thermal entanglement of the distorted Ising-Heisenberg spin chain: topology of multiple-spin exchange interactions in spin ladders
