@227]. In a purely electronic system with no local moment contribution to the entropy, we can readily obtain the behavior of the LAB in the low temperature limit, $$\begin{aligned}
\Gamma_H(H,T) = - \frac{d- y_0 z}{y_0 (z+\eta_H)} \frac{1}{H} ,\label{eq:3}\end{aligned}$$ which depends upon the exponent $y_0$ defining the temperature dependence of the specific heat, $C \sim T^{y_0}$, of the LAB phase. In the Weyl metal, $y_0=1$, and $\Gamma_H<0$, while for isolated double Weyl points, $y_0=2$, and $\Gamma_H>0$. Thus one may imagine a sign change of the Gruneisen number when field or strain is varied. Note that in Pr$_2$Ir$_2$O$_7$, there is certainly a large local moment contribution to the entropy, so that Eq.  is not literally applicable. Nevertheless, the LAB physics may play some role in this quantity.

In conclusion, we have described a novel NFL phase occurring in correlated strong SOC systems, with a natural connection to the pyrochlore iridates. Even with weak correlation effects, some of the phenomena discussed here can be observed with only minor modifications, and it would be interesting to search for them in HgTe. Future theoretical studies should include more comprehensive treatment of breaking of cubic symmetries, and the effects of disorder and doping.

We thank T. 