Multiband electronic transport in $\alpha$-Yb$_{1-x}$Sr$_{x}$AlB$_{4}$   [x = 0, 0.19(3)] single crystals
  We report on the evidence for the multiband electronic transport in $\alpha$-YbAlB$_{4}$ and $\alpha$-Yb$_{0.81(2)}$Sr$_{0.19(3)}$AlB$_{4}$. Multiband transport reveals itself below 10 K in both compounds via Hall effect measurements, whereas anisotropic magnetic ground state sets in below 3 K in $\alpha$-Yb$_{0.81(2)}$Sr$_{0.19(3)}$AlB$_{4}$. Our results show that Sr$^{2+}$ substitution enhances conductivity, but does not change the quasiparticle mass of bands induced by heavy fermion hybridization. 
Hyejin Ryu, Milinda Abeykoon, Emil Bozin, Yosuke Matsumoto, S.   Nakatsuji and C. Petrovic
cond-mat.str-el cond-mat.mtrl-sci