La$_{2-x}$Ba$_x$CuO$_4$ ($x=\frac{1}{8}$) $μ$SR data are inconsistent with spin stripe but consistent with spin spiral

Abstract

I analyze available $μ$SR data and show that it is inconsistent with the spin stripe but consistent with the coplanar spin spiral. The plane of the spiral coincides with the CuO$_2$-plane. The static expectation value of the spin is $S=0.37\times\frac{1}{2}$.

Figures (4)

• Figure 1: The spin spiral and different types of spin stripes, the numbers enumerate lattice sites. Arrows show directions of the staggered spin (every second spin is flipped up side down).
• Figure 2: Muon polarization vs time. Blue squares in all panels show T=5K data form Ref.Keller2014 The red curve in panel a shows the best fit of data in the spin-spiral model. The red curve in panel b shows the best fit of data in the "spin-stripe B" model. The red curve in panel c shows the best fit of data in the "spin-stripe C" model.
• Figure 3: Muon spin relaxation in parent La$_2$CuO$_4$, Ref.Budnick1987
• Figure 4: Muon polarization vs time. Blue squares show T=5K data form Ref.Keller2014 Panel a: The red curve shows the best fit of data with "modified 'spin stripe B" model at $p=0.9$. Panel b: The red curve shows the best fit of data with "modified spin stripe C" model at $p=0.9$. The white line in both panels represents the fit at $p=1$ that is identical to the spin spiral fit shown by the red line in Fig.\ref{['fit']}a.