Answered Questions

Positive relationships and employee motivation are searched differently. Motivation first... I would begin with the Organizational Leadership LibGuide. Choose the Resources for OL tab and then select ABI/Inform Complete.  I would start with "employee attitude" AND "job performance". Use the exact search, as the quotation marks and the "AND" will return a more relevant set of results. Use the left side toolbar to limit the results to the last 10 years, and look for peer reviewed and trade publications. I know you're looking at motivation, but attitude plays a big role in motivation, so I started here.

This search yielded possibilities including Parker, S. K. (2007). 'That is my job': How employees' role orientation affects their job performance. Human Relations, 60(3), 403-434. From the abstract: "...role orientation predicted performance more strongly than other work attitudes, including job satisfaction, generalized self-efficacy, locus of control, and job aspiration. Collectively, the findings suggest that the development of a more flexible role orientation represents a relatively unexplored avenue for enhancing employee performance." In other words, if a manager can motivate an employee to change the attitude of "That's not my job", performance will increase.

You can add relevant words to the search to further limit the results, for example, "employee attitude" AND "job performance" AND motivation. 

Another approach is to change up the wording. The search "employee motivation" AND "performance management" yielded only a few results when limited to the last 10 years, but among them were Nohria, N., Groysberg, B., & Lee, L. (2008, Jul). Employee motivation: A powerful new model. Harvard Business Review, 86, 78-84. and Bishop, M. (2013). How can I boost employee performance? Strategic HR Review, 12(2), 94-95.

For articles on positive employee relationships, search positive "employee relationships". Paste it into the search box exactly as it is here. You'll find articles such as Clawson, J. G., & Haskins, M. E. (2011). Career COMPASS: Navigating key aspects of employer-employee relationships. People and Strategy, 34(1), 46-55.

I hope it goes well with your department!