Please check the link on how to run a command on boot using cron. That should help you to start your binary on boot.

http://raspberrypi.stackexchange.com/questions/53684/how-to-write-a-initial-script-and-let-it-run-a-command-automatically/53719#53719

 sudo crontab -e
 @reboot /home/pi/temp_logger/temp_logger

This should be sufficient to run your cron job and I don't think you need that 

> "./temp_logger"

Also you don't need the "&". This is generally used to put a process in background. The only thing that you need to take care should be proper logging to debug in case of failures. I hope you have done that.