Magnetism in EuBCO and YBCO vortex states near and below T$_{c}$

By means of MaxEnt-$\mu $SR [1] analysis, we investigate transverse field $\mu $SR data [2] of EuBa$_{2}$Cu$_{3}$O$_{7-\delta }{\rm g}$EuBCO; T$_{c}$ = 93 K). Our focus is on a temperature interval near T$_{c }$to search for precursor effects, [3] and for predicted [4a] pseudogap loop currents above \textit{and} below T$_{c}$, already observed [4b] above T$_{c}$ for GdBCO. Further, we continue to study the field-direction dependence of the predicted [5a] and observed [5b] antiferromagnetism (AF) below 0.5T$_{c}$ for the vortex states in c-axis-oriented YBCO. This AF in and near the vortex cores is likely three-dimensional. In sum, magnetic roots of cuprate superconductivity are well plausible. Research is supported by LANL-DOE, REU-NSF and AFC. \\[4pt] [1] C Boekema and MC Browne, AIP Conf Proc {\#}1073 (2008) 260.\\[0pt] [2] DW Cooke \textit{et al}, Phys Rev B 39 (1989) 2748.\\[0pt] [3] B Aguilar, C Boekema \textit{et al}, Bull Am Phys Soc 37 (1992).\\[0pt] [4a] CM Varma, Phys Rev Lett 83 (1999) 3538.\\[0pt] [4b] T Songatikamas \textit{et al}, J Supercond {\&} Novel Magn 23 (2010) 793.\\[0pt] [5a] S-C Zhang, Science 275 (1997) 1089; H-D Chen \textit{et al}, Phys Rev B70 (2004) 024516.\\[0pt] [5b] C. Boekema \textit{et al}, J Phys Conf Series, 150 (2009) 052022. http://jpcs.iop.org/LT25