  State-of-the-art Ni/Ti supermirror neutron optics have limited reflected
intensity and a restricted neutron energy range due to the interface width.
Incorporating low-neutron-absorbing 11B4C enhances reflectivity and allows for
thinner layers to be deposited, with which more efficient supermirrors with
higher m-values can be realized. However, incorporating 11B4C reduces the
optical contrast, limiting the attainable reflectivity at low scattering
vectors, making this approach infeasible. This study explores various
approaches to optimize the material design of 11B4C-containing Ni/Ti
supermirrors to maintain high reflectivity at low scattering vectors and
achieve low interface widths at large scattering vectors. The scattering length
density contrast versus interface width is investigated for multilayer periods
of 30 {\AA}, 48 {\AA}, and 84 {\AA}, for designs involving pure Ni/Ti
multilayers, multilayers with 11B4C co-deposited in Ni and Ti layers,
multilayers with 11B4C co-deposited only in Ni layers, and multilayers with
11B4C as thin interlayers between Ni and Ti layers. Our results suggest that a
depth-graded hybrid material design by incorporating 11B4C inside the Ni and Ti
layers, below approximately 26 {\AA}, and introducing 1.5 {\AA} 11B4C
interlayers between the thicker Ni and Ti layers can achieve a higher
reflectivity than state-of-the-art Ni/Ti multilayers over the entire scattering
vector range.
