This thesis explores the interplay of magnetism, topology and symmetries in nanoscale devices.At the intersection of magnetism and symmetry, we will discuss the experimental demonstration of tilted spin current generated by collinear antiferromagnet RuO2, providing the first experimental evidence of a new magnetic phase known as Altermagnetism. We demonstrate that RuO2 can generate spin currents with the spin polarization aligned roughly to its Neel vector, consistent with the theoretical predictions of spin split bands. If the Neel vector is tilted relative to the sample plane, the polarization of the generated spin current has a strong component perpendicular to the sample plane which is useful for magnetic memory applications. At the intersection of magnetism and topology we explore topological insulators and their interaction with magnetic materials. We will discuss experiments on thermally generated spin currents by the topological insulator Bi2Se3. We find that Bi2Se3 generates substantial thermally driven spin currents with a spin Nernst ratio that is the largest among all the materials studied up to date. Strong thermally generated spin currents in Bi2Se3 can be understood via Mott relations to be due to an overall large spin Hall conductivity and its dependence on electron energy. In the last two chapters of this thesis, we will discuss heterostructures of topological insulators and two dimensional magnets. In these heterostructures, we observe quantized Hall responses corresponding to the parity anomaly state. In previous experiments by other researchers, these these states have been only observed at very low temperatures due to the presence of disorder in the devices studied to date. We demonstrate the creation of topological insulator (BiSbTeSe2)/magnet (Cr2Ge2Te6) structures, with pristine interfaces by exfoliation of van der Waals layer and mechanical assembly within a glove box, which leads to a strong proximity coupling between the topological surface states (TSS) in BiSbTeSe2 and magnetism in Cr2Ge2Te6. These structures demonstrate that when the Fermi level is within the exchange gap, the anomalous Hall conductance is close to half-quantized (e2/2h), even at the high temperature of 10 K. This is a factor of 100 higher temperature than any previous realization of a quantum anomalous Hall effect (QAHE) in a proximity-coupled TI/magnet heterostructure made by deposition, and twice the previous record for any QAHE system.