Scalarized black holes in new massive gravity dressed by a nonminimally coupled scalar

We investigate scalarized black holes in new massive gravity dressed by a nonminimally coupled scalar. For this purpose, we find the Gregory-Laflamme (GL) and tachyonic instability bounds of bald BTZ black hole expressed in terms of $m^2$ a massive spin-2 parameter and $\alpha$ a scalar coupling parameter to Ricci scalar by making use of the linearized theory around black hole. On the other hand, we obtain a solution bound of $0.161<\alpha <3\mathrm{/}16$ for achieving non-BTZ black holes with scalar hair analytically and a thermodynamic bound of $1\mathrm{/}8<\alpha <13\mathrm{/}80$ for obtaining consistent thermodynamic quantities. Without imposing the GL instability bound ($m^2<1\mathrm{/}2{\mathrm{\ell }}^2$), we find a very narrow bound of $0.161<\alpha <0.1625$ which is located inside tachyonic instability bound of $\alpha >1\mathrm{/}8+m_{\mathrm{\Phi }}^2{\mathrm{\ell }}^2\mathrm{/}6$ for obtaining scalarized black holes where $m_{\mathrm{\Phi }}^2$ is a scalar mass parameter.