Novel vortex phases and vortex manipulation in highly anisotropic superconductors by Scanning Hall Probe Microscopy (SHPM)

Scanning Hall probe microscopy (SHPM) has been used to demonstrate the interaction of pancake vortices with the Josephson vortex lattice in Bi2Sr2CaCu2O8+δ (2212) single crystals at large in-plane fields in the ‘‘crossing lattices” regime of highly anisotropic cuprate superconductors. SHPM has been used to study vortex structures in the interacting crossing lattices regime under applied in and out-ofplane magnetic fields. The interactions between the pancake and Josephson vortices (JV) depend on the values of crossing fields and temperature and the space between chains varies inversely with the in-plane field. These chains are clearly visible at very high in-plane fields HII~315 G over a range of outKirkuk University Journal /Scientific Studies (KUJSS) Volume 12, Issue 2, March 2017 ISSN 1992 – 0849 Kirkuk University Journal /Scientific Studies (KUJSS) Volume 12, Issue 2, March 2017 ISSN 1992 – 0849 of-plane fields 1.76.8 G at 85 K. The study of such chains allows a better understand the regime of crossing vortex lattices in highly anisotropic cuprate superconductors.


INTRODUCTION
Vortex structure in anisotropic layered superconductors such as the    and for one minute. If the resistances between Ohmic contacts were very low, the process was repeated for 30 seconds. This process was repeated until the resistance of Hall probe leads became around ten KΩ (see figure   1(c)). The last step is tip metallization. The process part is just the same as the Ohmic contact process except a tip mask is used in this process   Figure. (4): Schematic diagram of a scanning Hall probe microscope [5].
As a result, a coarse approach mechanism is started; after the system has cooled down to 77K. The Hall probe is mounted onto the piezoelectric scanner tube of a commercial low temperature STM system. The Hall sensor and sample holder assembly are referred to as the 'head' of the SHPM. The scanning tunneling microscope is an instrument in which a sharp conducting tip, attached to the piezoelectric drive (using stick slip principle), is brought close enough to a surface of sample BSCCO (2212).
So that, the electrons can tunnel between them. When the bias voltage (V) is applied between the wire and the surface, there will be a current known and an undivided part inside which takes care of the (z) motion as previously mentioned [6].

Vortex chain spacing as a function of in-plane field
The relationship between the applied in-plane magnetic field H II and separation of vortex chains at 85K in regime of highly anisotropic cuprate Hall probe microscopy (SHPM) was studied. The fields parallel and perpendicular to the sample plane were produced by two separate sets of coils which allowed one to vary the field components. It was observed that the distances between chains decreases with increase in (H II ) and the density of chains increases until they do start to interact strongly. Figure   5

PV structure of vortex chains at very high in-plane fields
The structure of Pancake vortex (PV) at very high in-plane fields (H II ) was studied while gradually increasing the out-of-plane field (Hz) at 85K using Scanning Hall probe microscopy (SHPM). In figure 7 shows inplane field is constant at 315 Oe and the range of out-of-plane field around (0 -6.8) Oe.
them were observed. The JV chains are close enough together that they interact strongly. In these images there is a row of "free" PVs trapped between each chain of decorated JV stacks especially, with increase outof-plane field over a broad magnetic field range 0 Oe-6.8 Oe. But, spaces between chains increased from range 3.4 Oe -6.8 Oe and these spaces depend on 1/ √H// 2 also on the PV density. As a result, we will seek to find new unidentified vortex matter phases at very high in-plane magnetic fields. The structure of JV stacks 'decorated' with PVs was studied at very high in-plane fields (H // ) while the out-of-plane field (Hz) was gradually increased at 85K. In the figure 8 shown the in-plane field was held constant at 315 Oe while the out-of-plane field was varied between (0 - optically [9]. The answer as to why GaAs/AlGaAs is better than Bi at low-temperature is as follows: At low temperatures, the signal noise ratio is generally very high > 88 times bigger than Bi. The maximum value of (I Hall ) for GaAs/AlGaAs is probably 40 A at low-temperatures. The Hall sensor GaAs/AlGaAs exhibits the highest carrier mobility's~10 5 Cm V -1 S -1 and lowest resistivity. Table 1 shows all details for both Hall-probe sensors at lowtemperature. Signal-to-noise ratio (SNR) 32 × 10 -5 2828 × 10 -5 Hall coefficient (R H ) 8 × 10 -4 Ω/G 0.3 Ω /G

CONCLUSIONS
The interacting JV-PV structures by SHPM imaging for highly anisotropic Bi 2 Sr 2 CaCu 2 O 8+δ (2212) single crystals at 85K was studied with a range of out-of-plane magnetic field 1.7 Oe -6.8 Oe was studied.
Through experiments on Bi-Hall probe at room temperature 300K and