Weides M, Kemmler M, Kohlstedt H, Waser R, Koelle D, Kleiner R, Goldobin E
Center of Nanoelectronic Systems for Information Technology (CNI), Research Centre Jülich, D-52425 Jülich, Germany.
Phys Rev Lett. 2006 Dec 15;97(24):247001. doi: 10.1103/PhysRevLett.97.247001. Epub 2006 Dec 11.
We fabricated high quality Nb/Al2O3/Ni(0.6)Cu(0.4)/Nb superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions. Using a ferromagnetic layer with a steplike thickness, we obtain a 0-pi junction, with equal lengths and critical currents of 0 and pi parts. The ground state of our 330 microm (1.3lambda(J)) long junction corresponds to a spontaneous vortex of supercurrent pinned at the 0-pi step and carrying approximately 6.7% of the magnetic flux quantum Phi(0). The dependence of the critical current on the applied magnetic field shows a clear minimum in the vicinity of zero field.
我们制备了高质量的铌/氧化铝/镍（0.6）铜（0.4）/铌超导-绝缘体-铁磁体-超导约瑟夫森隧道结。通过使用具有阶梯状厚度的铁磁层，我们获得了一个0-π结，其0部分和π部分长度相等且临界电流相同。我们这个330微米（1.3λJ）长的结的基态对应于一个自发的超导电流涡旋，该涡旋被钉扎在0-π阶梯处，并携带大约6.7%的磁通量量子Φ0。临界电流对施加磁场的依赖性在零场附近呈现出明显的最小值。
